When a customer places a pre-order a sound will play from your tablet indicating someone just has places a order.
All you have to do is press accept and the customer will receive a notification that you are preparing their order. Now the customer knows that he or she has to be at your coffee shop within the next 5 min. to pick up their coffee.
Tip. You can right their name on the cup to make the pre-order experience even more personalized.