I say yes because imprinting is involuntary, so I don't think it'd really matter just as long as the person the werewolf is meant to imprint on is around at the time. And, once they imprint they always know where their imprint is.
What an odd question! And yes, because it's involuntary. If they were drunk(lol), then they would probably have this really strong feeling that they wouldn't really understand and when they're sober, they would probably know why.