as mentioned - there is absolutely no need booking 330 days out if you are going to go via Asia anyway.

Just wait until the return is available for booking.

If you were going UA non-stop, then yes, maybe booking far out is wise, but for Asia, there are options via CA/TG that have plentiful availability.

If you are really worried - then book the outbound one-ways as insurance, and when return opens up - see if you can still book a round trip with stopover - 99% you will be able to do so. That 1% chance you wont be able to, you dont have to worry.

If you can book the round trip, cancel the oneways for a fee - or hope for a schedule change to cancel for free.