Print the orders out, if you have to, keep yourself organized and just take it one day at a time. I'm not overly stressed right now, but at Christmas, there were days when I thought I was going to go insane. Make sure you've got everything you need, and if you have to order stuff, make sure you do it well in advance. You'll be all right, and eventually, you will figure out your system. Some things just have to be learned as you go. :D
Congrats!