Feeding the right size mice/rats?

Well I bought two BP's this past weekend at a reptile show here in San Antonio and have no previous experience with snakes only lizards and more furry creatures. After talking to the guy I purchased the snakes from he told me that the smaller pastel boy was eating adult mice, and the larger normal girl was eating rat pups. The boy is about 3.5" around and the girl is 4.75". He also told me that in 2 feedings I should be able to switch the pastel boy to rat pups as well. Somehow I think thats a bit large for how young of a snake he is(he's from a fall clutch) especially seeing as the girl is over a year old and is just eating rat pups. Would an adult mouse for the pastel boy and 2 adult mice for the girl be ok?

Feed whatever work and is available/convinient to you rat or mice.

Try feeding an appropriate size prey (slightly smaller than the girth size) once a week.

Also note that adult mice and rat pups are similar in size so you just need to eyeball it.

So the maybe the girl is being underfed if Adult Mice and Rat Pups are the same size... Mice are easier for me to get then rats so I may just get 3 adult mice and feed one to the boy and 2 to the girl.

One of my girls is a lot smaller than the others but she eats the same size as early 07s.

Well based on there circumfrence do you think that the adult mice are sufficent? 1 for the boy and 2 for the girl?

I went and measured my little babies again, the girl is 1.5" in diameter and the boy is 1" in diameter.

Well I went ahead with feeding day today. Actually couldn't get to the big pet store with feeders and was reduced to going to petsmart but didn't wanna spend $10 on 2 damn mice. So I bought frozen ones they had and decided that for my bp's first meal in my care I would try to switch them to f/t. MISSION SUCCESS!!!!! The pastel male took a large adult mouse almost right away from tongs. The girl is in the middle of downing her first one right now and also struck immediately before I even had a chance to lower the mouse in. I'm gonna see if she'll take a second one a few minutes after she's done with the first.

Good idea going with the f/t at petsmart, they probably wouldn't sell you live anyways, since we're not allowed to. I hate that policy, but what can you do?

Eh if I had gone the live route I would have just told them they were pets. It would have been my first time buyin them so they wouldnt have known better