I would move him to the small mice and to a 10 day schedule. He should do well on that. The next time you move up a prey size, keep him on the 10 day schedule. As long as you don't offer him prey too large, you can keep him on 10 days until he's roughly 1.5 years old. I tend to move mine to a 2 week schedule sometime between 1.5 to 2 years.