It really depends....my adult male is very tame and the few times that he has mistaken my finger for food he has never applied any kind of jaw pressure when he did bite, and I hardly felt anything. He has never bit me as a defense. He also has been hand fed for much of his life which has helped make him a bit more personable.
My two juvies though are a bit on the snappy side and will bite HARD if they feel threatened when you have to stick your hand in the tank for whatever reason. So, like you I hope this calms down a bit as they continue to get used to the interaction.
Ironic though that the two small ones really hurt, and yet the decent sized 6" male is a big wuss. 
It can really vary from turtle to turtle.