Be sure that you always put the turkey in the oven breast side up. If your turkey comes with a pop-up temperature indicator, it will be located on the breast. During the first 2 to 2 1/2 hours, the legs and thighs will cook to approximately 100ºF. While The breast, at about 1 inch into the flesh, will usually still be at the soft ice point, which is about 25ºF. It's very important that at this point you begin to watch your turkeys breast temperature, as you do with any bird you cook. I use a digital terminator with a temp sensitive tip. You can also use a dial roast thermometer, but be sure it's inserted into the breast, because it is the slowest cooking part. After about 3 1/2 hours, the legs and thighs will be around 150 to 160ºF, and the breast, about 40 to 50ºF.