Thanksgiving is the best holiday in the world. I will punch anyone who disagrees. In our house, we are always hosting and we like it that way. Sure, we love our friends and family and love to have them in our home but, more importantly, I want the lion's share of leftover turkey and I definitely drinking enough booze that I shouldn't be driving anywhere.
For this Thanksgiving we actually made two turkeys. I smoked a smaller turkey (12lbs. I think?) and my wife cooked the 20 pounder in the oven. I had thought I was going to need to start smoking the turkey in the middle of the night, but that wasn't necessary. I think I started at 8am and the bird was definitely ready by 2pm. Heck, I think we could have served it at noon. But, nothing else was going to be ready so I ended up closing the smoker a little bit to let the temps drop down.
To prepare the turkey I rubbed it with sea salt about 24 hours before I was going to smoke it (don't ever use iodized salt for this) and then I patted the turkey dry. I then put it in the fridge uncovered. This helps the skin dry out and toughen up a bit. About 8 hours before "go time" I rubbed the turkey with some spices and a little more salt. I'm pretty sure I made my own rub, but I'm also pretty sure I just googled up "turkey rub" and went with one that looked good.
Once I had the bird in the smoker, I left the side door all the way open for a few hours. This got the smoker nice and hot and I was averaging about 350F. This really helped to crisp up the skin on the bird. I pulled the bird at 170F and proudly brought it into the house use the rib rack as a carrier. Then I covered it up with heavy duty foil for 30 minutes or so to let it get cool enough to carve.
I've heard of folks who will actually smoke the turkey hours before dinner time and then they wrap it really good with heavy duty foil, then wrap that in a towel and put the whole thing inside of a cooler inside. Your bird should stay above 140F for at least an hour or two if you do this.