It is perfectly acceptable to freeze stuffing. If stuffing is cooked inside a turkey, it needs to be removed from the bird immediately after it has been cooked.
Stuffing and gravy should be refrigerated or frozen within two hours of completed cooking to prevent bacteria from growing. If refrigerated, they should be eaten within two days. If frozen, they should be eaten within one month. While it is still safe to eat stuffing that has been in the freezer for longer than a month, it suffers a loss of quality.
Food stored in multiple containers and smaller quantities will get cold more quickly. For refrigerator storage, the temperature should be right around 40 degrees Fahrenheit.