This time of the year LAX-NRT-BKK is all one flight number 891. If you want those upgrades to drop sooner, book your flight in multi-flight segments LAX-NRT UA891 and NRT-BKK UA891 and they will drop per segment instead of having to wait for both legs to become available at the same time.

I am on 891 on 03/07 and cleared all the way over month ago - loads seem really low right now.


Cheers,
Chris