He's probably going to need live stimulation. I would wait a week before offering one. I'm still disgusted that a breeder sold a baby before it had its first meal to someone not experienced starting new babies, but that's a rant for another day.
Call around to small mom and pop pet stores in your area and see if any of them sell live feeders and have very small live mice (they may not know the term "hopper" so explain you want eyes and ears JUST opened).