Gonna be real boss, as a driver for DD, delivery drivers don't care what you ordered. They care about mileage, pickup & drop off times, and stairs. A $5 tip will cover most sane orders. $10 will usually cover insane orders / stairs.

If you're concerned about timing, tip $5 and then text them when they are assigned the order and let them know it is time sensitive and that you'll add cash tip on arrival for prompt delivery.