Rule of thumb is to avoid handling unless necessary after you get him, until he takes at least 2~3 meals for you.

For the most part, don't handle extensively when they're young and nippy to begin with. If he does show signs of stress/striking when you take him out, I'd just put him back and leave him alone more frequently. Don't worry!

There's nothing wrong with handling a baby ball just once a week, if that's only what the snake can tolerate so far.