No more than a day ahead is my recommendation. There are two ways you can make it ahead: Prepare the souffle as usual: Follow the recipe, but stop before baking. Store in the refrigerator: Once the souffle is assembled in the baking dish, cover it tightly with plastic wrap or aluminum foil and refrigerate it. Bake before serving: When you’re ready to serve, preheat your oven and bake the souffle as instructed. You may need to add a few extra minutes to the baking time, as it will be starting from a cold state.

You can also bake it and cover and store in the refrigerator, then reheat in the oven.