Good question but in my limited experience I've always been able to feed 2 days after a shed. In the picture where you are holding her it looks like she can handle eating a rat so if you are buying them at a pet store I think they call the mediums. The rats that my petco call small are actually larger than the medium frozen ones and do seem large but I think yours could handle it. I have one that has been fixed to associate mice with food and nothing else but I will work on that. The problem with mice is you have to offer several and then you have to wait for them to get the previous one down and you also risk over feeding and a regurge. I would just give her a medium or "small" rat a couple days after she sheds.