Sand boa feeding help

[Zoomonster13]

Hi everyone!
My new baby sand boa is eating great. Besides the first week which I know is normal. But he has grown so much already !! You can see it. Unfortunately I didnt have access to my scale the first 2 weeks I had him so i weighed him then. He is eating one pinky a week. Question is, since he is my first snake how do I tell when to feed more then just one pinkie and then move up sizes?
Please and thank you !

[Reptolover]

Does he beg? That could tell you

[craigafrechette]

The prey should leave a small but noticable lump in the snakes belly. If you're no longer seeing a lump it's time to upsize.