When a baby boy has his Bris we wish him "K'shaim Shenichnas L'Bris Kain Yikones L'Torah L'Chupa U'Lmaasim Tovim" - just like you entered the covenant so to should you enter into Torah, marriage, and good deeds. Should not Maasim Tovim be prior to Torah and Chupa? (Derech Eretz Kodma L'Torah)
Shaalos U'Teshuvos Atzei Broshim Siman 57 brings in the name of the Avudram and also in the Bais Yosef Yoreh Deah 265 that a parent has a Chiyuv to teach a child Torah and to make their Chuppa, and then it is the childs responsibility to do Maasim Tovim.
Likkuti Basar Likkuti (Agodas Hashas to Shabbos 137b) brings the following explanation from the author of "Iyun Menachem":
The Gemora (Kiddushin 29b) brings R' Yehuda in the name of Shmuel that one should marry first and then learn Torah, to which R' Yehuda responds that one is not able to learn Torah with the yoke of supporting his family. From this it is evident that before marriage it is easier to involve oneself in "Maasim Tovim" for then he has free time to learn Torah, and Chazal say (Kiddush 30) that "I created the Yetzer Horah, and I created the Torah as an antidote. If you involve yourselves in Torah you will not be given over to it." Since the obstacle to "Maasim Tovim" is the Yetzer Horah, and before marriage he had the Torah to protect him it was not so difficult to practise "Massim Tovim". However, after one gets married and assumes the yoke of supporting his family he is now susceptible to the Yetzer Horah who attempts to stop him from performing good deeds and he no longer has Torah to help. We therefore bless him that even after he gets married he should continue to do "Massim Tovim" despite the new difficulties.
It is known (Zohar Chelek Gimmel 257b, see Tur Orach Chaim end of Siman 417) that the three Avos correspond to the three festivals: Avraham, who characterized kindness, corresponds to the festival of Pesach when Hashem "passed over" the houses of the Jews and did not smite us. Yitzchok is the idea of severity, and the Torah was given on Shavuos "Mipi Hagevura", and Yaakov whose idea was Torah signifies the holiday of Sukkos (as Torah creates a "shade"- sukkah - for the soul).
We can similarly connect these three concepts to the three blessings of "Torah", "Chuppah" and "Massim Tovim". Avraham - kindness and charity - is "Massim Tovim". Yitzchok who is connected to Shavous, the marriage day between Hashem and the Jewish people, corresponds to "Chuppa", and Yaakov is the idea of "Torah".
In our personal G-dly service we need to emulate the actions of the three forefathers and thus must incorporate these three ideas. However, the balancing act between kindness and severity is often difficult - too much kindness can be inappropriate as can too much harshness. We balance the two by preceding the Chesed with Gevurah insuring that the kindness is directed to the proper channels. Thus the ideal order is to base ones actions on the directive of "Torah", which instructs us how and when to have the idea of "Chuppah" (Gevura) first, and then "Massim Tovim" (Chesed).
Alternatively, Likkutey Levi Yitzchok (Ha'aros to Sefer Hazohar, Breishis pg. 60, written by R' Levi Yitzchok Shnuerson, father of the Lubavitcher Rebbe) explains that Bris Milah corresponds to Rosh Hashana (a central theme of Rosh Hashana is the Zichronos of the "bris" between the Jewish people and Hashem commemorated by the blowing of the Shofar [see there for more connections between Rosh Hashana and Milah]). "Torah" corresponds to Yom Kippur when the second Luchos were given. The schach of Sukkos resembles the "Chuppah", and "Maasim Tovim" corresponds to Shmini Atzeres (he does not explain why).
Assuming one was bothered by the question, one could answer based on the Rambam's text of this declaration. Rather than the more familiar formula of כשם שנכנס לברית כן יכנס לתורה לחופה ולמעשים טובים (Just as he entered the covenant so may he enter the wedding canopy and good deeds), in Hil. Milah (3:2) he writes:
Just as you brought him into the covenant (bris), so shall you bring him into the marriage canopy and good deeds.
Since this is a request to the public the progression is logical. The bris is mentioned first since others (besides the baby) perform the entire ritual. Next, marriage is mentioned, since the community contributes to הכנסת כלה (care for the bride) and provides שמחת חתן וכלה (merriment for the bride and groom) and may provide further assistance in preparing the wedding, facilitating the marriage, etc.
Last comes the מעשים טובים; good deeds. The placement is obvious; one can request that the public help his son develop into a proper moral person, but this is ultimately the person's own choice.
Incidentally, the numerical value of כשם is 360. This is identical to the numerical value of עזר כנגדו; "a help-mate alongside him" (the expression used to describe Eve's relationship to Adam). If one were bothered by the choice of word, one could suggest that the word כשם, rather than כמו is used as a reference to marriage; the next stage in the life progression referenced in this blessing.
The word shem (name) means the essence of an item. Thus we see when Adam gave "names" to the animals he recognized their essences and integrated them into his view of the world. Thus, just as the entry into the bris was because of the essence of the mitzvah and not any external influence, so too should the other main mitzvos and critical moments of life occur.
תורה Bar Mitzvah - entering into the mitzos
חופה - Wedding - creating a new family
מעשים טובים - Now he can really start the "good deeds" of his family initiating his son into mitzvos by performing his bris.
I have seen the following explanation.
My own personal reason is that a child is not really an adult until after he has been married. Thus, a person is not really able to do "maasim tovim" until after the chupah. The maasim tovim are actually the deeds caused by raising and supporting a family (starting with his fulfillment of pru urvu). This begins the continuation of the chain of existence. The maasim tovim are the deed which include giving his sons a bris, teaching them (sons and daughters) torah and marrying them off.
Another explanation found at Understanding the Blessing given at a Bris Milah by Chaim B.