After he sheds it will be over a week since he last ate so any time after he kicks his shed you could try really. If you felt sfer you could give him 24 hrs after he sheds to relax. You could wait a week after he sheds if you were more comfortable. If it were me I would offer after he sheds and if he didnt seem interested I would wait 5-7 dys and try again. Or just give him what yu know he will eat and try the rat again at a later date. Sorry, rambled a bit...