I started-off with 25 per 30 days back in September 2018. That went on for some months until there was a Merit Source reallocation at the beginning of this year, moving up to a much more handsome figure (which I’ve currently exhausted and I’m now running through my personal earned sMerit backlog).

Edit: I think there are lower starting points is some local boards. I recall reading someone stating a lower amount than 25. Let's see if I can find it.
Ok, I can stop searching now .... I've got an old PM that hints a Merit Source with a lower amount back then, but still in the two digits.