Feeding Prekilled mice to my Python?

I just got my python sunday.Im waiting to feed him until this weekend just so he gets used to his new home.The breeder i got him from said he was feeding him pinkies.I really think he could take a little bigger then that.I have read alot about mice hurting the snakes.If he has never at prekilled or thawed mice would it be hard to have him go from live to dead?I really dont want him to get hurt.Hes about 6 months old i believe. still a baby and small.