One to two days ahead, make one pan of cornbread according to the box instructions. Let this sit out overnight and get a firm (almost hard) crust.
Place sausage in a large, deep skillet. Cook over medium high heat until evenly brown. Crumble, drain and set aside.
In a skillet, cook onion and celery in butter until soft. Remove from heat, allow to cool.
In a large bowl, combine crumbled cornbread, sausage, onions and celery. Add sage, garlic powder, salt and pepper. Mix well.
In 1/4 cup increments, add chicken or vegetable broth to stuffing mixture. Toss gently until evenly moist. Loosely stuff in fowl or casserole dish and bake at 350 degrees F (175 degrees C) for 30 minutes or until heated to 160 degrees F (70 degrees C).