when i went for mine, the lady emailed me, telling me to have a cold fizzy drink before i went to wake him up, i drank a bottle of coke on the way there, and its a 20 min drive and he was fast asleep, i had to do the whole lying on my side and she shook him about so he woke up for 5 mins then went back to sleep

so id say half a hour before and like the others said, chocolate too or something like that ? have fun xxx