This is a variable thing. The more alcohol that is consumed, the longer it takes for it to be eliminated from the body. To be on the safe side, 24 hours should elapse (even though several hours is...
Alcohol leaves the bloodstream at the rate of .015 of BAC per hour. So a very high BAC of .150 would be gone in 10 hours and a BAC of .08 would be gone in five hours and 40 minutes.