We always opened one gift on Christmas eve too - but ours was a book! I like to think it was a clever idea my mom had to get us up into our room and stay there with something to do (whether we slept or not).
Christmas morning was always hanging out at the bottom of the stairs until mom and dad said it was OK. Stockings first, then presents. HOWEVER! We didn't always know which ones we ours. Sometimes my mom just labeled them with numbers or colors or switched names (so mine were labeled my sister's, etc.). It always made it interesting and kept us from shaking the presents too much. :)