The "Lost Chronology" project begins on the day of the crash (with Desmond not pushing the button) and ends with Jack dying. The pre-crash flashbacks will be cut together and released later as a "Season 0," while the flash-sideways will be an epilogue miniseries/season/episode/whatever.

The "Chronologically Lost" project begins with the birth of Jacob and MIB and follows along until Jack's death. I dunno how they're gonna be doing the flash-sideways timeline, though.

Point being, if you want you can check each of these projects out and see what feels better to you.