Is its weight okay?

Hrm lets do a little math here...

Lets assume the snake is born at 100g and it eats every week, in all equations we will assume that the prey weighs exactly 15% of it's body weight and the snake was born on the beginning of October (so 4 weeks in october, november, december, and 3 in January, totally 15 weeks).

Assuming the snake will gain 10% of the consumed items weight: 125.02g

25%: 173.71g

50%: 295.89g

This really depends entirely on how much weight the snake will gain per prey item. However, your snake weighs 120g (or so) as such the prey item you should be aiming for is probably around 18g (at 15% which I believe is the typical recommended size).

As for the prey item it should be eating weanling mice or fuzzy rats based on Rodent Pro's weights. From here the size is based on how often you feed it. If you continue feeding every 5 days it should build up in size nicely.

The guy i bought it from said he always fed it live..
But when i tryed it.. He was scared of it..
It only eats frozen.. And i dont dangle it in front of him or anything. It has to be completely still..
After i got thur the last hoppers i have ill feed him bigger ones..
I have 2 left,
so if i feed him tomorrow.. And thursday would that be okay?

I'd feed both hoppers tomorrow

I thought you werent supposed to feed 2 at a time??

Eh you can. Just weigh them, if they are more than 30% of it's weight I'd only feed it one. which I strongly doubt.

How do you figure that out?
Just divide them by the snakes wieght??

Your snake is roughly 120g, then they really shouldn't weigh more than 36g. I'm not saying that is a good general rule for feeding but if you're thinking of feeding it a decent bit quickly I'd not go over 30%. In general your snake should probably be eating around 18g items for every time you feed.

Okay thanks so much

That is a little small for a 4 month old ball python, it should probably be more around the 300-400g range. It should have no problem taking down two hoppers in one meal and should probably be eating an adult mouse or a rat pup from now on. The snake will eat both meals if it wants them and wont if it doesnt :)