Thanks. Those are player approximations probably. But helpeful regardless. I was able to confirm in the logs the 2:15 for 2nd wave so far. I added the times to the related UB Strategy post in the public section.
Knowing the spawn times helps us CC/prepare for the next wave as you know. As we do the event more, we can confirm the rest of the intervals.
Thanks for posting Xab, see you in game.