When does Heavensward begin ?

[Morningstar1337]

I think that the xpac's narrative starts earlier than the X.0 patch, specifically I think it lasts from X.4 to X+1.3. However that depends on what the previous narrative focused on. ARR is wierd becuase it placed emphasis on the elemental primals and thus that arc "ended" in 2.4 (Dreams of Ice)...

However the seeds for Heavensward were patched in that patch as well, matchup to the trend of beginning the expac narrative two patched in advanced and the 2.X cycle also death with revitalizing the content of Eorzea on a societal level, given the apocalyptic effects of Bahamut's rampage as well as the Scions eventually moving to Mor Dhona, neutral ground that is independent of the citystates. In a way the Primal arc served a similar niche to the Raids and the Trial sideseries, a running narrative that ends at X.5...except again that plotline ended a patch early (technically so do the 8 man raids).

The primals were basically a way to bridge the ARR arc with the HW arc, overlapping with both and making it more "seamless", but I should note that had Moggle Mog XII were moved or made optional, then that arc would had ended at the 2.3 patch, bringing the ARR cycle more in line with the xpacs' narrative breakpoints.