Does it have to be an exact month? Or can it be from post 54900000 until post 55111681? The latter is what I used.
For your convenience, I've added links to the profiles instead of just usernames, see loyce.club/other/Aveatrex.html. It was a quick fix, so unfortunately sorting by userID failed.
Note: this only counts users who posted on public boards (so not in Investigations). It doesn't include users who have been active (for instance reading the forum or sending a PM) without posting.
It's probably interesting to check this list for Banned users.
For the past 7 days, I have Active users and top posters on Bitcointalk.org in the past 7 days.