I like watching America's Test Kitchen. I've also got a huge cook book of their's. This season they had an episode talking about turkey,
https://www.americastestkitchen.com/episode/533-outsmarting-thanksgiving this link is from their website and is time sensitive. They don't keep all their episodes available on line.
Now i'm used to cooking turkey the way my mom did it. She started out cooking the turkey the way her mom did. But learned more from friends. Gone is the turkey baster and all the extra work. My mom's grandma came over from Italy. So Thanksgiving hasn't been in our family for generations. There's nothing like getting up at 6:00 in the morning to start shoving things up a birds... well stuffing. Then taking hours and hours to cook. A 13.5 bird would have taking me four and a half + hours to cook.
In the episode the last cooking time was 1:30 minutes. They did a twelve pound bird. So some simple math put that at 7.5 minutes of cooking per pound after the initial 500 to 425 at 45 minutes cooking. So at 7.5 minutes a pound my bird should be done in two hours and 26 minutes total cooking time. Cooking for 1:41 minutes at 325. For safety and common sense I do have a probe thermometer. I'll go a bit higher in temp than what they suggest. Now I didn't factor in the first cooking time per pound of 45 minutes. Or three minutes and 45 seconds a pound. ( twelve pounds for 45 minutes = 3:45 a pound ) Because there is only a difference of two minutes. Yes that could burn cookies and set a good stake on edge. But not much for a large bird. I'm looking forward to this. We'll either have an all American toasty turkey. Or lunchmeat with home made bread. : )
And as a side note. That bird has been sitting in my icebox for five days now. Took it out today to start the process. There was STILL ice inside?

Do they freeze these birds down to absolute 0 or what???

Merry Christmas everyone!