I see some people feeding babies pinky mice and/or 'rat pups'.
Pinky mice are way too small for any BP.

You need to feed a prey slightly smaller to equal your BP's girth size.

I would recommend you to feed whatever the breeder/store was previously feeding this way you are less likely to have a refusal.

Your priority right now is for you to get your BP to eat.

Switching whether it is to another type prey or F/T if the animal was fed live should be secondary and additionally it will be more easy to accomplish once the animal is well established.