It is unsafe to stuff the turkey ahead of time. The chilled stuffing in the turkey will not reach a safe temperature before the turkey is done. To be safe the turkey should reach a temperature of 180 degrees F. and the stuffing in the body cavity of the bird should reach 165 degrees F. It's fine to make the crumbs or bread cubes ahead, but the stuffing should not be completely prepared ahead if it will be used to stuff a turkey. If the stuffing is to be baked in a casserole, it can be prepared in advance and chilled. The baking time will need to be increased by about 15 to 20 minutes.