Yoko

So my boyfriend and I got another ball python on Friday and I just thought I should update you guys.

We got her and she was in a terrarium with only some rocks and a bowl for water.. She was eating 4-5 "medium" sized mice he said, every 14 days. Which I found incredibly odd. She still has eye caps on, and when he gave her to us she was "borrowing" one of his other snakes heat sources.. Which also only hit temps of 73.. And on top of all of this there were soaking wet spots all over the tank whit no thermometer or anything to check the humidity with.. So now we have a UTH, a thermostat, hides, new substrate and proper husbandry in her enclosure as of two days ago, when do you guys suggest we feed as well as what size?

Ps, we were told she was 3 years old, and she weighs roughly 770 grams

I'd let her settle in for a week before offering her a medium adult mouse.
That's on the smaller side but I find that best when getting them back on track.
After the snake starts eating well bump up the size to large mice.

3 years old and 770 grams, oy
Good luck getting her back on track and healthy again :)

Thanks, yeah. The guys we got her from really had no idea how to take care of a snake. I mean a ball python, and not so much as a hide? It was terrible.

I'm very confident in her getting healthy though, she seems like she can pull through

Someone was telling us 10-15% of body weight for a feeder.
Is this correct?

He said that he had her for 2 years, so she could be a bit younger, but never the less that is very small.

But yeah he told us he was feeding 4-5 small mice every 10-14 days, and it kinda confused us lol.

She seems very friendly, the only changes we have made were putting her on new substrate and giving her hides and what not, along with a UTH.

For an underfed snake I'd stick closer to the 10% rule than 15% per week at least till you get the snake used to it's new home and settled in nicely.
Try 10% of the snakes weight weekly which means 2-3 young adult mice if she'll take them.
Or you can try to switch the snake to rats so you can feed 1 prey item weekly, but that's up to the snake and if it will eat rats.