My personal limit is nothing in the 12 hours before flying, but then im never a heavy drinker. If I ever did drink far more than usual, I would plan to not fly at all the following day.
On a related note.. a couple of friends I went flying with in the states would often partake in smoking weed in the evenings - though not if they intended to fly the following morning. They treated weed with the same approach as to drinking before flying, which i guess makes sense. Does anyone have any figures on how long the imparing effects of this stay around in the body?
(and tangentially to this - it would show up in a class 1 medical renewal, wouldnt it? I dont know whats involved for the class 1, never done one)