Interesting question. No real hard way to figure any answer. I wasn't even quite sure the first one was over yet. Or that it's even started. Really, really hard to say.
They indicated that there would be a few, and that there would be "lots" of chances to get an invitation, but that could mean anything from 1 round every week to 1 round every year for the next decade.
They only told "a Few" that mean MINIMUM 2 each month.
Not really. There's is no "definition" of a few.