I don't consider 4 pints a big night out, but more than what I would normally drink at home on an evening, and I would certainly allow more than 8 hours before report if drinking that.....
I need 8 hours sleep most nights (unless its an early), and to stop drinking 8 hours before report for a longhaul flight means less than 6 hours sleep. Not a good idea before operating a longhaul trip in my opinion.