A post can now be scheduled up to a year ahead — with Later in Instant Post, with One post per video, and through the Publishing API (it was 180 days there).
Later offers quick picks, a calendar you move month by month, the hours of the chosen day, and Other time. A date in another year shows its year, for example «Tue 5 Oct 2027», in Instant Post, Your posts › Scheduled, Change time and the calendar. A time further away is refused with «Pick a time within the next year.»
The phone app uses the same limit and the same dates.