I would just be patient with them. Shipping is stressful. Float them for a few minutes to match the tank temp, open the bag, reach in and grab the discus and drop them in the tank. No other acclimation is required. You may want to turn the lights off for a few hours. If they don't eat right away, just give them some time. If they are healthy, they will eat...
What do you plan to feed them?