Christmas is such an exciting holiday for my children. Me personally, I explain to my children the purpose of Christmas while allowing them to celebrate by giving and receiving gifts. If they receive a gift earlier than Christmas day, depending on where it's from I allow them to open it if they want. The gifts that are at home underneath our tree are not allowed to be opened until Christmas Eve. Well they are allowed to open 1 gift that Eve and on Christmas morning they are allowed to open the rest.
We have a tradition in our family that we open gifts from each other on Christmas Eve. We open the other gifts on Christmas Day. My mom still insists I wait until Christmas Day for some gifts.