You can easily make manicotti ahead of time. Follow all the steps of preparing manicotti up to the baking but instead of baking, place the covered baking pan into the refrigerator.  To bake it the next day, preheat the oven to 350°F and let the pan warm up a little on the counter while the oven is preheating. Bake for about 40 minutes with foil on top, take off the foil, and bake for another 10 minutes.