Casual Dining Issue

We run a casual dining restaurant and we are in the final evaluation of Softtouch. People order at our counter, pay for the food and then sit down in one of the dining areas (inside and outside). When the food is ready, we bring it out to them. Similar to how a Sweet Peppers Deli operation. So the payment for the food happens before the customer receives the food. Operationally, I need to be able to track how long the customer is waiting for the food. But once I process payment, the ticket is closed.

This can't be that unusual. Anyone got any hints ? It's defeating my business guys and it's down to this showstopper. Thanks