Multiple Superdays question

So I have a superday for Risk at a BB, however, they have multiple sessions (6...) and I think it's a bit much. I can only attend one of the later ones because the first few ones are during my finals week (and the very first one was reserved for the top candidates I believe).

I read on here that there isn't a quota, so what are the odds that they fill up before the 5th/6th ones? Has it happened before?

Also, how many candidates should I expect at each session?

Should I try to go in between finals?

Thanks in advance