Happy Thanksgiving and Bring on the Turkey Math

I am cooking a big turkey today for our entire family gathering. That I have done before. But this time I am cooking it in an electric roaster. I googled how to do it and received numerous hits with instructions with lots of variations. The roaster temperature given ranges from 325 to 375 degrees. Okay, so guess I'll go with 350. The time for cooking a 12-14 pound turkey was 3 to 3 3/4 hours, while the time for a 14-16 pound turkey was 3 3/4 to 4 1/2 hours. So it looks like I should cook the 14 pounder for 3 3/4 hours. The turkey needs to be finished at 12, so I need to back up the time to cook it till 8:15. But since I need to get it out of the fridge, wash it, remove the neck and bag of innards, I need to back up the time a little more. Phew! I hope when we sit down to enjoy this bird that my math was correct.