Ordinarily I'd agree with the above advice. However, IAD-HND flights have generally been speaking been more easily upgradeable than most other international flights of late. Of course, by March 2025 that could change. My two most recent flights IAD-HND and vv. cleared seats to non-revs.

So, I would not rule out hope for a March set of flights, when it's not high tourism season, assuming OP is willing to fly midweek when there's less business demand.

OP - flights generally open up 330 days out, but prices are usually higher, even for economy, then than they are likely to be closer in. Of course, you can book if you want . . . but your upgrade request is likely to be in waitlist for most of those 330 days.

As for schedule, figure it will be about the same as it is now . . . other than switching from NRT to HND, the flight schedule has been almost identical for close to a decade - depart IAD about 12:30, depart HND about 4:30 in winter, 3:30 in DST.