Thanksgiving Turkey prep!

Prep is going well so far. DH is under strict orders to relax (a hard job for him, seriously). Son and daughter are helping a little. I’m boiling the potatoes in cream and water. About ready to start cooking the green beans. I’m most nervous about the turkey. I never know how long it will take to cook. And I love the instructions to take off the foil an hour before the turkey is done - how do you know when that is?