Originally Posted by SpinzCity

It generally happens 6am or 7am. Oddly, as opposed to normal days-out EUA's that pop me into a seat, these early morning day-of-travel EUA's always wind up saying "seat unassigned", and I have to select a seat. This suggests that this is a 'different' kind of upgrade--it may in fact be a processing of the waitlist--it's hard to know (I always abort check-in at 23:59 after being told that I have been put on the waitlist).