Ah, for the good old days, before we knew about food safety. We could blithely stuff and cook the bird without realizing it might send our nearest and dearest to the emergency room the next day. But now we know a few simple precautions will avoid after-dinner disaster.
Dressing must reach 165° at its center in order to be safe. Use an instant-read thermometer to check it.
It's best to cook the dressing in a separate dish. The cavity of a turkey is a bacteria-laden place, and if the dressing doesn't reach the desired temperature, the bacteria can cause food poisoning. And you may have to cook the bird to the point of dryness before the stuffing reaches the required temperature.
If you simply must bake the stuffing inside the bird, then be sure to: