Chance,

You apparently have studied this out quite a bit, so I'll address my questions on this, to you.

I have read/heard in other places, that not only now, but even back at the time of Jesus' earthly ministry, there were different calendars.

Were the Pharisees, Sadducees, and the Essenes each working off of different calendars?

I had read, that because of this, and their understanding of how to use the calendars,

that, at that time, there were actually two days for sacrificing the lambs at the temple for passover.

That Jesus and his disciples kept the passover on the first of these two, but that the priests and Sadducees on the next.

Included with that, back then, were differences about whether the feast of unleavened bread started the day after passover, or whether it began on the same day.

Do you know any more about this?

Also, that, back then, there were differences on how and when to keep the feast of firstfruits.

What about the fall feasts? Were there differences, back then, about the when and how of those three feasts, as well?