After seasoning turkey, cook for 30 minute on 550.
Turn oven down to 450 degrees and cook for 1 1/2 hours.
Do not open the oven at all during this cooking time and the turkey is cooked complete (providing you follow the directions). It really doesn't matter how big or how small the turkey actually is. It will be fully cooked as long as the directions are followed and the oven door remains closed during the cooking process!