There are volumes of threads on how AS' automated upgrade system works (or sometime doesn't work) but I find myself in a quandary and I hope worthy of it's own thread....

I'm looking to fly ORD - PDX later in the month and am MVPG. The only fare class left is M, which is eligible for an instant upgrage. However, there is no U currently. There are also only middle seats but F = 8.

If I book the flight, do I just end up on the regular upgrade list and compete with all others for upgrades at the time of complimentary ugrades for my elite tier?

Or are there sweeps prior to that as AS releases U space where my UG may clear prior to the window for my elite tier?

Thanks!