You can actually try it out from home, just don’t actually submit the order.
Go to your My Disney Experience app, pick a restaurant, for example Cosmic Ray’s in MK, pick the half hour timeframe you’d like to eat in, pick out all your food, and that’s it. Then, when you’re a couple minutes from showing up at the restaurant (I always seem to ride Space Mt before Ray’s, so I do this part when I hit the Space gift shop) you just hit “I’m here, prepare my order” in the app and wait outside until you’re notified it’s ready, then go in, pick it up at the counter and enjoy.
edited to add: I always know where I’m eating lunch in each park, and about when I’ll be hungry, so I just do my order before I leave my hotel in the morning. Dinner is less concrete, so I either snack, or have an ADR.