You should arrive at the boarding gate at least 15 minutes before your departure time for a domestic flight and 45 minutes if you are traveling on an international flight. Baggage check-in time requirements vary by airport.isit delta.com from 24 hours to 30 minutes* prior to a domestic flight within the U.S. or 60 minutes* prior to an international flight, go to Check In, and follow the simple instructions. To access your itinerary, you will need one of the following: 1  A SkyMiles number and Password.