What a wonderful and high gain question!
The creation of man, meaning Adam HaRishon, was on the morning of the sixth day of the six days of Creation (Bereshit 1:26-31). (The creation of Adam HaRishon was only after the passing of the twelve hours of night on the sixth day like is found in Midrash Chemdat Yamim to Bereshit 5:1 and also Sanhedrin 38b in the name of Rabbi Yochanan bar Chanina. That days in the Torah begin with the dark of night, like it says in Bereshit 1:5, “…and there was evening and there was morning, one day”.)
It began at the first hour of daylight and was completed in the seventh hour of daylight of that same day.
This was the point when Adam and Chava were married. That at this point, they both existed as separate individuals and were joined as mates in a pair bond like is expressed in tractate Yevamot 62b-63a starting with Rabbi Tanchum and concluding with Rabbi Elazar who says:
Any man who does not have a wife is not a man, as it is stated: “Male and female He created them…and called their name Adam” (Genesis 5:2)
A very significant detail of Rabbi Elazar’s comment concerns the usage of the term Adam (אדם), which as used in the beginning of Bereshit has multiple different meanings (like for example, Adam אדם in the sense of dust from the earth מן האדמה and also Similar to G-d, above דומה לעליון).
Abarbanel in his commentary to Bereshit explains that it can also mean either the entire species of modern man, or a particular individual human being, or it can appear as the personal name of the individual in this narrative (See בראשית ד, קלב ד״ה האמנם בדרך וכו׳ and also שם ה, קלד-ה ד״ה זה ספר תולדות אדם וכו׳).
Properly comprehending the meaning of the written text of the Torah is dependent upon knowing which meanings apply for each expression.
Their first consumation (physical relations) between Adam and his wife was in the eighth hour of daylight on the sixth day of Creation.
This is enumerated in many places within the literature of the Torah, but a good single source to reference, which cites many other sources is Seder HaDorot, First Millennium.
At this point it is important to note that these Days of Creation are counted according to G-dly time, like we learn from Moshe Rabbeinu in Tehillim 90:4 which says:
One thousand years are in Your eyes like a day of yesteryear that has passed.
After the first seven days of Creation (the six days of the week and the first Shabbat), time is counted like we count time currently, in this world.
In this context (meaning specifically as the paradigm relates to the creation of Adam HaRishon), the first week mentioned at the beginning of the Torah spans 7000 years in our current timeframe. Each hour of a 24 hour day during that first week account for approximately 41.6 years as we currently count.
(It is important to note that the paradigm of the narrative in Bereshit also applies simultaneously to the Creation of the entire Universe.)
The best way to conceive of this is in terms of the concept of time dilation like is discussed in Albert Einstein's Special Theory of Relativity. A good discussion of this subject in relation to traditional Torah teachings can be found here.
The effect of time dilation is manifest either by approaching the speed of light, called relative velocity time dilation or by close proximity to a great mass, called gravitational time dilation.
Absent any mention of Adam HaRishon being accelerated to the speed of light, the other possibility would be proximity to great mass.
This enters into the subject of dark matter and dark energy. It is present everywhere and accounts for approximately 80% of the mass of the universe. But its effect on material existence as we experience it is usually almost undetectable.
The primary evidence of Dark Matter today is the presence of Cosmic Microwave Background Radiation. By this description, dark matter seems to align with the concept of the Lamp of Darkness (בוצינא דקרדינותא) mentioned in the the commentary Mikdash Melech, 1:15a:6-12 to the Zohar, Bereshit 15a.
That the Lamp (meaning the source) of Darkness refers to the moment at the beginning of Creation just prior to the first manifestation of Light in the Created Universe in Bereshit 1:2-5.
According to the description given by the European Space Agency, at this point light and matter were inseparable meaning so closely bound because of the extreme heat that atoms were unable to coagulate allowing empty space, so light could not radiate. Therefore the entire universe was opaque, meaning dark and black (the Lamp of Darkness).
As the universe cooled, atoms began to coagulate (צמצום) allowing light to begin to manifest everywhere, like is described on the first day of Creation, light without a light source that is everywhere (יהי אור ויהי אור). That first light is still observable today and is called Cosmic Microwave Background Radiation.
This paradigm of cooling, coagulation and manifestation of light is actually described by the fourth Lubavitcher Rebbe, known as the Maharash, in a quote from him, explaining the meaning of the word Kavod, for the fifth day of Nisan in the book, HaYom Yom which says:
אאזמו"ר [אדוני אבי זקני מורי ורבי] אמר במרז"ל [במאמר רבותינו זכרונם לברכה] לא מקומו של אדם מכבדו אלא אדם מכבד את מקומו, כבוד יש בו שני פירושים: לשון כבדא כמרז"ל [כמאמר רבותינו זכרונם לברכה] כבד לב פרעה נעשה לבו ככבד. ולשון כבוד, גילוי אור מקיף נעלה.
That Kavod, Glory (as used by Isaiah 6:3, the whole world is filled with His Glory, just like Cosmic Microwave Background Radiation) has a meaning like liver, which is cold and coagulates (thickens blood) and also a meaning of the revelation of highly Sublime, all encompassing light.
This concept of time dilation also relates to the statement found within Torah teaching that the distance from the earth to the Rakia is 500 years Chagigah 12a and 13a, Yerushalmi Brachot 9:1:13 and Pesachim 94b).
This concept reveals one of the underlying paradigms of the whole of Creation. It is the underpinning to the union and oneness of the spiritual with the physical, the seven Heavens and the earth, male and female, and husband and wife.
That this union is the source of life and is the underlying meaning of BeMidbar 14:21
which states:
וְאוּלָ֖ם חַי־אָ֑נִי וְיִמָּלֵ֥א כְבוֹד־יְהֹוָ֖ה אֶת־כׇּל־הָאָֽרֶץ׃
Before (meaning prior to) everything, I am life and the glory of G-d fills the whole world.
Ultimately it is a statement that G-d is one.
The Nachash was among the land dwelling creatures that were created during the 12 hours of night during the sixth day like is stated in Bereshit 1:24 or possibly in the fifth day pertaining to the Taninim (תנינים) like is mentioned in Bereshit 1:20-23.
This second possibility follows what is mentioned in Midrash Chemdat Yamim to Bereshit 1:21. It also seems to be the understanding of the Yalkut Shimoni to Bereshit 12:3-4 which says the Taninim are also called Leviatan-Nachash and emphasizes that they were called Taninim because they do not have a mate. (Which would lead to its extinction.)
The wording of Chemdat Yamim cited above also indicates the nature of the relationship between the Nachash and Adam HaRishon, meaning the modern human species as a whole.
It establishes the paradigm of the Animal (Animating) Soul (נפש הבהמי׳) and the G-dly Soul (נפש אלוקי׳ היינו נשמה) which in kabbalistic nomenclature is also called the Soul of Intellect (נפש השכלי׳) and (which has no ability to interact with the material world directly). That the Animating Soul is the intermediary between the material existence and G-dly/Spiritual existence. And this is in keeping with the wording of the Alter Rebbe at the end of chapter 1 in the Tanya, section Likkutei Amarim, beginning with the words, "אך ביאור הענין על פי מ״ש רח״ו ז״ל וגו׳" and the beginning of chapter 2.
The creation of the Nachash preceded the creation of Adam HaRishon which began with the first hour of daylight on the sixth day like is enumerated many sources like Seder HaDorot at the beginning of the first millennium or Pirkei d'Rabbi Eliezer 11:6-7.
The Nachash is a type of proto-human being (it was intelligent, could speak and walk upright) that preceded in the order of the creation before Adam HaRishon.
In an archeological sense it relates to any of the pre-Cro Magnon proto-humans, like Homo Erectus, Homo Heidelbergensis, Homo Floresiensis, Denisovans, Neanderthal and other subsumed human sub-species.
This follows the language of Yedidyah HaKohen of Alexandria, also known as Philon (Philo) of Alexandria in his discussion of the giants to Bereshit 6:1. (See Kitvei Philon, Mosad Bialik edition, volume 4, part 2, pg.11, where he discusses our species of human being in contrast to the species related to the giants mentioned in the Torah.
These proto-humans are generally described as the ten branches of pre-Adamic peoples, specifically: קיני, קניזי, קדמוני, כנעני, אמרי, חתי, פרצי, חוי, יבוסי ורפאים
These ten sub-species of proto-humans occupied ten different lands around the globe. In particular, the Nachash was from the branch known as Chivi (חוי) like is discussed by Rabbi Shlomo Molcho in Sefer HaMefoar (ספר המפואר,דרוש עשר ארצות כנגד עשר ספירות ד״ה דע כי שם חוי הוא נחש כתרגומו וכו׳). This also follows Targum Onkelos to Bereshit 3:1 which says:
וְחִוְיָא הֲוָה חַכִּים מִכֹּל חֵוַת בְּרָא דִּי עֲבַד יְיָ אֱלֹהִים וַאֲמַר לְאִתְּתָא בְּקוּשְׁטָא אֲרֵי אֲמַר יְיָ לָא תֵיכְלוּן מִכֹּל אִילַן גִּינְתָא:
These proto-humans are also referenced in the Torah (see BeMidbar 13:33) as giants (ענקים), physically larger than modern humans or Nefilim (נפילים) from the root הפל which linguistically relates to a miscarried fetus. The idea being that these branches of proto-humans will ultimately fail and become extinct or be subsumed by modern humans through interbreeding with the descendants of Adam (see Bereshit 6:4). In this context, it is worth noting that there are still genetic traces of these proto-humans in a small portion of the human population today.
As Rabbi Molcho explains, the branch of the Chivi sub-divided into further branches which were called the Girgashites and the Refo'im.
These proto-humans are all enumerated in Torah in Bereshit 15:18-21, Devarim 2:11, Devarim 2:20, Devarim 3:11 and Devarim 3:13 among other places in Tanach.
In this context, the subject mentioned in Midrash and Zohar of Chava being seduced and impregnated by the Nachash has an entirely new and deeper meaning. That she was impregnated and possibly raped by this proto-human at about the same time as the first conception between Adam and Chava (something alluded to in Tehillim, chapter 23 which recalls Chava collecting food in preparation for the first Shabbat) and that the first two children (Kayin and Hevel), or at least one of them (Kayin) were actually from the seed of the proto-human. This follows the view of Midrash Chemdat Yamim to Bereshit 4:1 that begins, "And Adam knew Chava, his wife...".
To understand this correctly in terms of the human genetics, it would mean that Kayin and Hevel because they had such widely different traits were fraternal twins, meaning conceived from two different eggs (Chava hyper-ovulated) and two different sperm, that of Adam and that of the Nachash.
This is also supported in the midrash Sefer Yashar to Bereshit discussing the killing of Kayin by Lemech many years later. It says that Tuval Kayin who was helping his grandfather Lemech hunt, misidentified Kayin at a distance, who looked not like a human being, but like a wild animal meaning a proto-human.
In the ninth hour of daylight of the sixth day of Creation, Adam was given his commandments and in the tenth hour the transgression took place, meaning eating from the tree.
In the eleventh hour of that day was their judgement by G-d.
Finally, in the twelfth hour of that day, they were sent from Gan Eden to Kedem (note that Seder HaDorot cited above says they went out to the people, meaning the proto-humans), which in this world corresponds to Beit Shean in the Jordan River valley. (See also VaYikra Rabba 29:1, Pesikta d’Rav Kahana 23:1 and Zohar, BeShalach 16:232)
This Upper world/State of Existence concept, that there are upper worlds which parallel this lower world, also relates back to the concept of time dilation mentioned above.
That there are universes on different energy levels or spiritual levels which are all bound by the same paradigms of the Creator. This is associated with the concept of fractalization. Everything which exists in the lower realm, comes from and is a consequence of its parallel in the higher realm. But what is perceived from one level to the next is not the same.
This can be understood in the context of the light receptors in the human eye. Human beings in this world generally perceive the visible light spectrum. But there are other ranges outside of the visible spectrum, both higher and lower which the human eye does not detect. They are constantly present and may even effect us yet are not perceived with our eyes.
This parallel land, where they were created is called Eldah (אלדה) in Sefer HaYovelim, Bereshit, end of chapter 3 3:32 which relates linguistically to the land of their birth.
This sequence is also how it is recounted in Pirkei d'Rabbi Eliezer, chapter 11:27-47.
The first Shabbat is also explained there. chapter 20:1-13 How G-d kept the first Shabbat while Adam and Chava were in a transitional state outside of time.
It goes on to explain in chapter 20:14-23 that G-d provided light for Adam to say the first havdalah at the close of the first Shabbat.
Like is recounted in Seder HaDorot, it was at this time, starting on the night of motzi Shabbat, following that first Shabbat, that Adam separated from Chava in this world for 130 years as part of the avodah of his teshuvah. This follows the teaching of Rabbi Meir in Eruvin 18b and is also detailed in Pirkei d'Rabbi Eliezer, chapter 20:29-38.
Even more detail about this episode can be found in the beginning of Sefer Raziel which is also called Sefer Toldot Adam Kadmon (beginning with Adam's first three days of prayer, see זה תפלת אדם הראשון כו׳).
That similar to the behavior of the Jewish people at Har Sinai in their preparation for receiving the Torah, higher states of kedusha and taharah are required, including the separation of husband and wife, in preparation for intimacy like is described in Shemot 19:14-15.
It should be noted in regard to this 130 year separation that it is a measure for measure judgement from G-d on Adam relating specifically to the sin he transgressed.
That Adam added to G-d's commandment concerning eating the fruit from the tree of Knowledge of Good and its opposite like is found in Bereshit 2:16-17 which says:
וַיְצַו֙ יְהֹוָ֣ה אֱלֹהִ֔ים עַל־הָֽאָדָ֖ם לֵאמֹ֑ר מִכֹּ֥ל עֵֽץ־הַגָּ֖ן אָכֹ֥ל תֹּאכֵֽל׃
וּמֵעֵ֗ץ הַדַּ֙עַת֙ ט֣וֹב וָרָ֔ע לֹ֥א תֹאכַ֖ל מִמֶּ֑נּוּ כִּ֗י בְּי֛וֹם אֲכׇלְךָ֥ מִמֶּ֖נּוּ מ֥וֹת תָּמֽוּת׃
Following the giving of this commandment to Adam HaRishon, G-d built a mate for Adam from a part of Adam's body. That mate was to be named Chaya, as in the source (Mother) of all life (Bereshit 3:20). But her name was changed to Chava, meaning the source of culpability, his wife. (Regarding this letter transformation of Yud and Vav, see the commentary of Radak to Bereshit 32:31-32)
But Chava had not been built and was not present when G-d gave Adam HaRishon his commandments. She was taught this knowledge by her husband, Adam, who added to G-d's (negative) commandment like is seen in Bereshit 3:2-3, where she recounts to the Nachash what her husband had taught her was G-d's commandment.
וַתֹּ֥אמֶר הָֽאִשָּׁ֖ה אֶל־הַנָּחָ֑שׁ מִפְּרִ֥י עֵֽץ־הַגָּ֖ן נֹאכֵֽל׃
וּמִפְּרִ֣י הָעֵץ֮ אֲשֶׁ֣ר בְּתוֹךְ־הַגָּן֒ אָמַ֣ר אֱלֹהִ֗ים לֹ֤א תֹֽאכְלוּ֙ מִמֶּ֔נּוּ וְלֹ֥א תִגְּע֖וּ בּ֑וֹ פֶּן־תְּמֻתֽוּן׃
That Adam added to G-d's prohibition when teaching his wife (even though it is suggested that he was only building a fence to avoid an accidental transgression by his wife), a transgression enumerated in Rambam's commentary to Mishnah Sanhedrin 10:1 enumerating the 13 Foundations of Jewish Law which says:
היסוד התשיעי
ההעתק והוא כי התורה הזאת מועתקת מאת הבורא הש"י לא מזולתו ועליה אין להוסיף וממנה אין לגרוע לא בתורה שבכתב ולא בתורה שבעל פה שנאמר לא תוסיף עליו ולא תגרע ממנו וכבר בארנו מה שצריך לבאר ביסוד זה בפתיחת זה החבור:
That the judgement that Adam should separate from his wife for 130 years corresponds to what Adam added to G-d's commandment, "וְלֹ֥א תִגְּע֖וּ בּ֑וֹ פֶּן־תְּמֻתֽוּן׃
".
That the Hebrew word, lest (פן), has a gematria of 130. And that this is associated to the connection of Heaven and Earth (meaning Husband and Wife, that Adam is from the Earth and Chava, his wife is from Heaven. See Bereshit 2:7 and Yevamot 39a) like is hinted at by the ladder (סלם) of Yaacov's dream whose head reached to Heaven and whose foot rested upon the Earth (see Bereshit 28:12) and the location (Mount Sinai) where the Torah was given (see Shemot 19:11 סיני). Literally described as the joining of Heaven and Earth. That these Hebrew words all have a gematria of 130.
That through Adam adding to G-d's commandment, he had diminished the revelation of G-d's presence in the world and caused a separation, so to speak. Adam made this separation through his speech and this precipitated the actions between the Nachash and his wife and the events which followed it including his separating from his wife for 130 years after that first Shabbat. At the conclusion of that process of Teshuva, he and his wife were blessed by G-d and given a new son (שת) to replace their son (הבל) and to preserve his species (אדם).
Concerning the birth of Kayin and Hevel, as contrasted to the time of their conception (which was in the eighth hour of the sixth day of the six days of Creation), their birth was much later. Kayin was born in the 65th year following that first Shabbat and Hevel was born in the 72nd year. They also had a sister named Avone, who would later become the wife of Kayin, who was born in the 93rd year after that first Shabbat. Kayin murdered Hevel in the 100th year after that first Shabbat. All this is recorded in Sefer HaYovelim, beginning of chapter 4:1-3.
This is also discussed in the commentary of Don Yitzchok Abarbanel to Bereshit, cited above.
Abarbanel brings this in the name of the author of יוסיפון in his other book called ספר הקדמוניות. This text of יוסיפון is also mentioned and partially copied in Me'ir Einayim by Azarya ben Moshe DiRossi of Edom (Rome), who says it is based on an earlier book called ספר העתים which was written by Philo of Alexandria.
This tradition attributed to Philo (also known as Yedidyah HaKohen, the leader of the Jewish community in Alexandria in Egypt and who actually records his travels to the Temple in Jerusalem while it was still operating, places him chronologically at the time of the Tannaim, 1000 years before the Abarbanel.) actually originates from Sefer HaYovelim.
Sefer HaYovelim is counted among the Sifrei Chitzonim. But the beginning of this book states that it was written by Moshe Rabbeinu at G-d's command at Har Sinai. That Moshe was to write the history from the beginning of the Creation divided into Yovelim. Remnants of this tradition are also found in Sefer Yashar. The Jews of Ethiopia (Beta Yisroel) also preserved this tradition. But most surprisingly, with the discovery of the scrolls from the Qumran community (the Essenes), the near complete text of Sefer HaYovelim has been found in the original Hebrew. In this context, it is worth noting that Philo writes about the Essene community in his other works. He was familiar with their teachings.
To recap, Sefer HaYovelim 4:2 says that Kayin murdered Hevel at the beginning of the third Yovel, meaning 100 years after the exile of Adam and Chava from Gan Eden, like the Abarbanel states in his commentary cited above.
This means that Kayin would have been 35 years old and Hevel would have been 28 years old. It is in connection with the murder that there are additional indications that Kayin and Hevel were actually born after departure from Gan Eden like is mentioned above.
Midrash HaGadol to Bereshit 4:13 recounts the details of G-d's interaction with Kayin following the murder. That G-d was trying to lead Kayin through the process of Teshuvah. This is detailed even more in Midrash Agadah, Bereshit 4:8-9.
It is clear that Kayin was unaware of knowledge of G-d, like his father and mother possessed from when they were in Gan Eden. This would be the consequence that he had been conceived in Gan Eden but wasn't actually born until much later, in this world, when G-d's presence was greatly concealed.
It goes on to bring out that even though Kayin's Teshuvah was accepted by G-d, it was not complete Teshuvah (תשובה גמורה) and for this reason required that Kayin go into exile from the land where his father and mother resided.
It goes on to explain in Sefer HaYovelim chapter 4:7 that Adam and Chava mourned the murder of Hevel for 28 years, and in the thirty-second year after Hevel's murder, Adam rejoiced (possibly over the completion of his teshuvah and the period of his separation from his wife) and conceived a second time with his wife from which was born a son who was called Shet (שת). It adds that in the 36th year after the murder of Hevel, a daughter named Azura was born to Adam and Chava.
It continues and explains that Kayin married his sister Avone, who gave birth to his first child, Chanoch, 200 years after the exile and expulsion of Adam and Chava from Gan Eden.
You have also asked about the other descendants of Kayin and on this subject it is worth noting the discussion of this subject in Philo in his commentary of the Torah mentioned above. Philo suggests, based on the grammar of the text that the additional offspring from Kayin are not actual human beings, but paradigms for negative human behavior which leads to extinction from this world.
This is also the emphasis from Midrash Agadah, Bereshit 4:17-18. Perhaps this points to extinct or subsumed proto-humans discussed above in regard to Bereshit 6:4. This is also referenced in Sefer HaYovelim 4:22 which refers to these proto-humans as Irim (העירים).
And finally, in Sefer HaYovelim 4:29-32 it records that Adam died 930 years after the six days of Creation and the first Shabbat. It relates this to the idea that 1000 years are like a single day in relation to the testimony of Heaven (Sefer HaYovelim 4:30 and Tehillim 90:4) and that this reveals the meaning of Bereshit 2:17 which says:
but from the tree of knowledge of good and bad, you must not eat of it; for on the day that you eat of it, you shall die.”
And in the year after Adam died, Kayin was killed (by Lemech). But Sefer HaYovelim says that the buildings which Kayin had built collapsed and the stones from the collapsing buildings which struck him, killed him, measure for measure like he had done to his brother Hevel. Once again, this alludes back to the names of Kayin's descendants (the letters (also of names) are called stones) mentioned above in the name of Midrash Agadah, in particular Irad (עירד) which means to crumble from the world.
So the chronological order of the events listed in your question is:
The creation of the Nachash.
The creation of Man, meaning Adam HaRishon.
Eating of the Tree of Knowledge of Good and its opposite.
Expulsion from Gan Eden.
The first Shabbat
Disappearance of the original Gan Eden and Tree of Life.
Adam separates from Chava and his process of teshuva begins.
The birth of Kayin and Hevel.
The murder of Hevel (With G-d's judgement and Kayin's turning from G-d, meaning he becomes a wanderer following the murder of his brother, his process of teshuva begins.
The birth of Shet (See Seder Olam Rabbah 1 with the commentary of the Vilna Gaon and Seder Olam Zuta 2:1)
The birth of Kayin's first child, Chanoch. The enumeration of his other children may be an indication of the process of his teshuva.
Kayin may have completed his teshuva (if that occurred at all) when he stopped being a wanderer. This was marked by his building the city named after his first son.
Kayin's death. There are two accountings of his death providing various details. One is from Sefer Yashar which recounts the hunting accident with Lemech and Tuval Kayin. The other found in Sefer Yovelim says that the home that Kayin built (in the city of Chanoch) collapsed and he was crushed by the stones of that building, measure for measure equating with how he murdered his brother.
