Re: Recessed light install: thru ceiling drywall or subfloor above?
As Debbie suggests, cut the holes from the ceiling side, then assess if you can chase wires or not. If not, then pulling the floor upstairs will be the least destructive course of action.
Be prepared that when you pull up the floor that you'll have to clean glue off the joists and probably replace the subfloor material if it's glued down. If no glue you're ****en.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!