When I get a discus shipment, they go into a darken tank and I'll leave them alone for 24 hours before putting in some food. In your case, I'd even drape the tank with towels to give them a little privacy. Not only are they stressed from the trip, but they've never been in such an exposed situation before. Discus are kept crowded together throughout their lives so a huge tank can be intimidating for small fish.
Good luck, Willie