I would give him 5-7 days to get used to his surroundings and then feed him. It's not going to hurt him to miss a meal. He needs a little time to adjust to his new surroundings. You don't want him thinking there is a mouse living in there with him right? Good Luck, and remember not to handle him for at least another 3 days, then food, then 2 days digestion, then play time!