He's look quite nice actually. I checked our records on our male who was 145 when we got him from 8Ball. He was on fuzzy rats then, usually one per week, occasionally two. Fuzzy rats are between 8 and 13 days old. He went to rat pups about 6 weeks later when he'd gained some more size and girth. Small pups though of about 14 - 18 days of age, not the bigger pups that are close to weaning age. Now that he's 510 grams he easily takes a nice plump just weaned rat each week.

Hope that helped. Every snake is different though so just pick a prey size that is the same or preferrably slightly smaller than his biggest girth and he should do just fine. Lots of access to fresh water and good healthy prey items will help him do the best. A vet visit and a fecal float is always a good thing when you get a young snake from a pet store as they are pretty much of unknown background.