Last year, I overcooked a turkey that I was to take to a Church Thanksgiving meal. Fortunately, I did grill it the night before. The meat was dry and chewy. I carved the bird and placed all into a cheap aluminum roasting pan, then covered it with the juices from the drip pan. It sat in the fridge for about twelve hours. By the time it was reheated gently in the oven (it was ready by noon), the turkey was super moist and tender. The meat had re-absorbed the juices lost during the cooking process.
If I can rehydrate a bird after drying it out, by letting it sit in its own juices, think how great it will be if you cook it properly, then immerse it in its own juices overnight.
The answer to your question is, yes, you can cook it the day before. Then you can garuntee that the bird will be perfect when served, even if you get too busy doing other things. Of course, use yoru meat thermometer and cook to a temperature of 165' F. and it will be perfect anyways.
Oh, and with that turkey that had been overcooked, those who ate it told me it was the juiciest, most tender turkey they had ever had.
Seeeeeeya' Chief Longwind of the North