S.W.
It's a little unusual that a three year-old to not have had chocolate. I don't remember when I first gave my daughter chocolate, because it wasn't a big deal. I remember at first she didn't even like it and would spit it out. I believe in all things in moderation, and my daughter, now 8, rarely choses to eat candy even though I don't restrict it.
My daughter has a friend whose mother restricts all sweets from her diet. Then when the girl is with her grandmother, she constantly whines and begs for more candy and dessert, or sneaks it when she thinks no one is looking. She already is developing a weight problem. So yes, restrictions can backfire.