If you set it up and put stuff on it from your computer, then when she gets it and plugs it into her computer, everything will be erased. Also, a soon as you turn it on, it begins the set-up where you have to make/put in an Apple ID which contains credit card information so the purchasing and downloading of content, free or charged. If you put in your information, then you will be charged any time she buys something of value.
So my suggestion, when she gets it on Xmas day, let her set it up. It takes about 10 min (that's how long it took me).