Concurrent calender or timing of Passover in the time of the late 2nd temple

Question

I have read in secondary literature that the calendar or the regulations, in particular on the celebration of Pesach found in the rolls of Qumran differ from the Rabbinic tradition that is observed until today. As to current research, is the Qumran practice likely to represent the common practice of the time or did that community observe rules that differed from the rulings of the Temple?

Side information is welcome, concerning discussons of different opinions in the Gemara, the exact difference between the Rabbinic tradition and the Qumran rulings. The difference to Samaritan cult is only of interest if it goes along with Judean/Galilean practice of that time.

Answer 1

There's a Qumran document in which a leader of theirs documents their differences with the mainstream/proto-Pharisees. So I'd imagine that the mainstream were already doing their Passover dates the non-Qumranic ways.

Rabbi Dr. Shneur Leiman points out that in the Qumranic Book of Jubilees, Passover was always a Wednesday, and the Omer always harvested on a Saturday night. He points to the mishna Menachot 10:3:

קְצֹר. שָׁלשׁ פְּעָמִים עַל כָּל דָּבָר וְדָבָר, וְהֵם אוֹמְרִים לוֹ הֵן, הֵן, הֵן. וְכָל כָּךְ לָמָּה. מִפְּנֵי הַבַּיְתוֹסִים, שֶׁהָיוּ אוֹמְרִים, אֵין קְצִירַת הָעֹמֶר בְּמוֹצָאֵי יוֹם טוֹב:

Each response happened thrice, and the crowd replied "yes, yes, yes!" Why all this pageantry? Because of the Boethusians, who had said the Omer is not harvested right after the holiday.

Leiman thinks this refers to the Qumranic practice, whereby the Omer was never harvested just after the first day of Passover.