So here is what we (I really) know so far:

Time Period 3 is the first Campaign, which we are told takes place right after ANH. So ANH would be between time periods 2 and 3. This is further backed up by the fact that Luke can only join in time period 3 for now and has to leave before time period 5.

Time Period 5 is RTH which is set during (the intro) and after Episode 5. This suggests that Episode 5 is between time periods 4 and 5. This is why neither Luke nor Han can come to RTH as allies. From hear on all is speculation based on Ally side missions. Boba disappears after time period 5. This suggests one of two things: 1 By the end of RTH, the Rebels are no longer on Yavin IV (this is what I believe), or 2 There is a reason dealing with the characters that Boba tapers out 1 time period before Vader. (On a side note, it bothers me that Vader can be searching for Luke in time periods one and two. I will personally change it to Ben, Galen Marek, or Kota, when playing it before the IA campaign.) So with Vader leaving after 6, I would guess that Episode 6 is set between me periods six and seven. If this is true, we know we still have two pre-ANH big boxes, A big box for time period 4(Pre-ESB), 6(Pre-ROTJ), and 7(Post-ROTJ).

Great stuff.

Makes me real glad I use the IA Campaign tracker so I don't mess this stuff up when I'm setting up for a new campaign.

Boba disappears after time period 5. This suggests one of two things: 1 By the end of RTH, the Rebels are no longer on Yavin IV (this is what I believe), or 2 There is a reason dealing with the characters that Boba tapers out 1 time period before Vader.

ESB pretty strongly implied that the alliance had already abandoned Yavin IV as a base. I think the mission works fine with the rebels delivering to a base in a different system (and Dark Obsession shows that the focus on time periods is the character recruited over other factors). I figured the most likely reason for Boba being 1-5 is that he spent some time before RTJ hanging out at Jabba's palace rather than actively hunting bounties.

Boba disappears after time period 5. This suggests one of two things: 1 By the end of RTH, the Rebels are no longer on Yavin IV (this is what I believe), or 2 There is a reason dealing with the characters that Boba tapers out 1 time period before Vader.

ESB pretty strongly implied that the alliance had already abandoned Yavin IV as a base. I think the mission works fine with the rebels delivering to a base in a different system (and Dark Obsession shows that the focus on time periods is the character recruited over other factors). I figured the most likely reason for Boba being 1-5 is that he spent some time before RTJ hanging out at Jabba's palace rather than actively hunting bounties.

Strongly implied? They moved to Hoth and got found again by the probe droids and had to run... don't think they had a base after that because at the end of ESB the fleet was moving which then attacks Endor.

Star Wars: Rebellion shows that the Rebel base can be on any planet at any time, and events can happen in any order.