I think I know the answer but wanted to be 100% before I do any booking--if I'm AS MVP Gold and book a full-fare Y ticket, I would only get an instant complimentary upgrade if there is U space available? I always thought (at least for other airlines like DL) that if you purchase a full fare ticket your complimentary upgrade is instant at time of booking; but it sounds like, at least for AS, it's only instant if there's U space, otherwise you go directly on the upgrade waitlist?

Thanks you guys!