First ball and i got a couple questions

[Skeet]

Hey guys, I'm new to the forum and to ball pythons. I've got 2 corns but they don't even compair. Anyways, I get Jezebel a week ago and have pretty much left her alone the whole time. She's just under 2 feet and I was told about a year old. The Breader told me that he fed her an adult mouse last wednessday(the day before i got her). He told me before i got her that she was taking medium rats but then when i got there he said he had just fed her a mouse. I'm confused and i don't know how to figure out food size. Also he said he was feeding live, and i wanna get her on frozen/thaws.
Sorry that was long but my 2 questions are:
1) When should i atempt to feed her?
2) what would be the best thing to offer her?