Long time reader, first time poster. Really hoping to nail the use of FT forum acronyms on my first try

I'm DL PM booked ATL>DTW>PEK departing this Saturday on PS (Fare Class G.) I recently started traveling to Asia for work and only just learned the "call asap after you book to be on the mileage upgrade waitlist" trick. I called this afternoon and spoke to someone who I think was at HIBRES, and she put me on the waitlist for a mileage award upgrade. As of right now, the DL website is showing 4 award seats still available on Delta One for my flight. I know if my upgrade hasn't cleared in advance I don't have a super great chance of getting one, but I'm curious what my chances are. Does the time that I actually check in make a difference? Anyone have any insight as to when/how often upgrades clear?

I'm assuming that by tomorrow 24 hours before the DTW>PEK leg, I'll know one way or the other, but wondering if someone with more experience in this situation has some insight. I've heard plenty of horror stories about DL taking off with open Delta One seats, so I'm not getting my hopes completely up.