I'd say 2-5 like svilleantigo said, or 2 tallboys like max power if I'm in the mood. Nothing too wild, but it definitely loosens me up and helps me be a little less of a baby about committing to things. I don't smoke weed at the moment, but when I did I'd have to skate for a bit to get warmed up, smoke some, and then skate and things would be fine. If I smoked before skating at all it was like my brain wasn't communicating with my legs properly.
One time when I was in Savannah visiting some friends we played skate in the alley behind their place, and we'd take a drink every time we got a letter, which quickly devolved into every time you miss a trick in general. Then we cruised over and skated this building foundation that had been abandoned down the street that had a small gap over this metal thing, a bigger gap on the other side where it was higher and you could gap some grass and the sidewalk into the street, and was just smooth concrete and a ton of fun. One of the better sessions I've ever had.
A bad time was cruising back to my apartment from my friend's place one time, we had gotten pretty sloppy and when I went to push I pretty much just did the splits. Like, did not pick my back foot up off the sidewalk at all. Ended up just carrying my board as I stumbled home.