My daughter lost her first tooth at age 6. We made the swap while she was sleeping, no problem. When I woke her up for school the next morning, I asked her about the tooth fairy, and she excitedly found the money under her pillow. She spent about ten seconds being excited before she looked at me straight in the eye and said suspiciously, “Mom, are you the tooth fairy?” Busted, lol. We still reward her when she loses a tooth because it’s fun. It took her another year to come to terms with Santa, though.