Hi United_Fan... this is the former SFOintern.
United has upgraded your upgrade confirmation
as a premier from 24 to 48 hours prior to departure.
So you will know whether you have been confirmed an upgrade 48 hours prior to each departure by way of the method you selected (pager, e-mail, wahtever). You shouldn't have a problem on ORD-SEA, from the loads I've seen on that route. LAS-IAD shouldn't be a problem either because it's a 757.
Premier Execs get confirmation 72 hours prior to departure time.
1Ks I beleive it is 100 hours? I forget...