they say after a week!! But mine took one afta 1 day, but thats only bcz the man i got him from hadn't fed him that week yet that i tried! I would leave it a week!!
You really need to leave your snake alone for a week to settle, changing water only then after the week offer food, when he's eaten, you then need to leave him for 2-3 days to digest. Its a long wait, just had to do it myf, but its worth it.