Santa vs.Tooth Fairy

We tried to convince Nathan that it would be very cool to have Santa and the Tooth Fairy come on the same night. But the tooth just wasn't ready (L. central incisor). I'm getting a bit anxious because his permanent tooth is already growing in behind the loose one...potentially creating quite the "Billy-Bob" situation. His dentist told me not to worry as it would move forward on its own. Hmm, how early can they get braces?