Data point: stopped by this (Sunday) afternoon a little after 4:30. Had a sign up saying they were taking waitlist only. As I checked in for the waitlist, I heard one of the other agents say that the waitlist was 35 deep. I got on the list at 4:38, and was notified at 4:51 to return. Elected not to as we would be departing shortly anyway.
When we checked in, the agent said "see you very soon" (or something to that effect). I am unclear on whether that was a standard message (I assume), or because he thought that I was not #36 on the waitlist. The two guys ahead of me did get turned away because they were using PP not associated with a CSR; the agent told them the lounge starts taking that card around 6 (and presumably earlier in the day).