You've heard my opinion via PM already, but I'll share with everyone.
I'd wait at LEAST until after the first feeding. I know how hard it is to resist handling a new snake, and I myself am guilty of handling a snake before its eaten a few times for me.
If you are going to handle your snake before it's eating consistently then keep the handling sessions short. A couple minutes here and there shouldn't do any harm. If your snake isn't eating for you every week, cut the handling until its eating again.
Most ball pythons are fine with handling, but there are some that get very stressed and it can cause them to go off feed. You don't want this to happen if its a baby.