my advice differs from those mentioned above. i start out with mice on every ball python i dont even attempt rats until the 5th meal or after.
with the mice i use i never use hoppers, they are like little crack heads that scare ball pythons easily. i use small fresh weaned mice to small adults for babies in the 65 gram range. it seems big but they usually eat without hesitation and handle the size quite well.
they grow very fast with this size as well. when they hit 100 grams i offer rats and havnt had one refuse rats yet. they usually hit 100 grams within 5 -7 meals. less than a month on average.
just my methods but choose your own.....they can go MONTHS AND MONTHS without eating before its an ACTUAL issue
adam jeffery