Should I stop them from nibbling on me?

Ben and Timothy are about 9 weeks old and they've started nibbling on my fingers, probably smelling food on my fingers. Should I tell them "No" when they do that and pull my hand away? It doesn't hurt, now, but I'm afraid when they grow up they'll do the same thing, only then they'll be stronger and nibble harder... kinda like with a puppy that will gnaw on your hands or jump up on you. you think its cute when the puppy does that, but then it grows up and thinks that behavior is still okay, but when it jumps up on you it nearly knocks you over.

Also, Timothy nips my arm when my arm is in the way, much like Jack does (though this is pretty rare for Timothy) and it kind of hurts and I'm sure it will hurt worse when he's grown, so do I firmly tell him "NO" when he does that? I'm not sure what the best method is to train him.

my rabbit also did yhis but she seemed to grow out of it im not sure if there is a training technique to stop rabbits doing this.