When the soufflé is baking in the oven, the air pockets grow from the heat and the mixture rises to pop out of the ramekin ever so slightly. When the soufflé is removed from the oven, the soufflé begins to deflate slowly due to the lack of heat. So to make the soufflé look it’s best, you must serve it immediately after removing from the oven.
What if you are having people over and are too worried about dinner to focus on a semi-complicated dessert like soufflé? Well, the answer is simple. Make the soufflé ahead of time and get the soufflé batter in the ramekins. Next, freeze them, tightly covered, until 20 minutes before you want to serve them. Then you can just pop them in the oven and serve at your convenience so you don’t have the stress of making a dessert and dinner all at the same time. I would suggest making them earlier in the day.
Also, you should note that the soufflé is still delicious even if it sits to room temperature and has deflated and will actually keep in the refrigerator for up to 3 days. But, if you want the traditional dramatic soufflé effect, it must be served immediately.