Found it! In 2023 there were 526 entries into this event.
526 x 20,000 chips = 10,520,000 chips
10,520,000 / 30 = 350,667
However, the big blind ante appears to continue through the end of the tournament (I think), making the BB effectively more like 300,000 at the 150K/300K level. So that is pretty close to the formula I mentioned (which I may not be remembering correctly).
If all that is right... 29 levels at 30 minutes each plus a 45-minute break plus four other 15-minute breaks = 15.5 hours of play time plus 1.75 hours of break = 17.25 hours.
That takes you to about 3:30 am, I believe.
Another rule of thumb I’ve seen is that it’s likely to end when the big blind + the small blind = 80% the size of the starting stack. That would result in a much shorter tourney here... 80% of the 20K starting stack is 16,000, which would result in the tourney ending more like around levels 17/18, or about 10-11 hours total. Sounds a bit quick to me.