It may seem like it's not moving, but in last year's thread, only 7 people posted to say they were accepted off the waitlist while 38 people were accepted in total. So the forums may not be an accurate representation of how much the waitlist is actually moving.
By this time there were only a few people off the waitlist last year who posted and 38 got in from the waitlist, so very few people posted their waitlist offers
I did a quick check of the 2019 acceptance thread and 8 people said they got in the first few days of June. There were more who posted the following couple weeks and the 2019 waitlist moved less than the 2020 waitlist. Assuming that everyone on the waitlist wasn't on the forums, there is significant movement after the deposit (usually starts at the very end of the day on June 1).
If there is similar movement, high waitlist should be close to clearing early June. Unless the high waitlist is 30 people lol