I couldn't start any sooner because our Christmas book collection isn't large enough yet. But I wrapped them all up and told the girls they could open one tonight and one every night until Christmas. I think they were a bit confused. They were more than happy to read the book Ash unwrapped but couldn't figure out why I only let them open one. Hahah! I'm sure they catch on eventually.
(these are the only "presents" under the tree. the real ones are wrapped. they are just waiting for me to have a moment to put ribbons and name tags on them, then i'll move them.)