Wasn't there a case about 10 years ago of a guy who had flown from Elstree to Cambridge and back swigging vodka from a bottle before crashing.? Now that is too much alcohol.
Personally, if I am flying with 24hrs, I dont drink at all although I will confess to once having a training flight with a bit of a hang over - slow flight too. Stalls are not good in that state.