Hello everyone! I’m Giantakeshi14 How Long Befoer a Delta Flight Can I Check-In? This applies to both domestic and international flights. For domestic flights, it's best to arrive at the airport at least 2 hours early and check in at least 30 minutes before your flight. For international flights, you should arrive at least 3 hours early and check in 1 hour before departure. Online check-in closes 30 minutes before domestic flights and 1 hour before international flights. Checking in early helps make your travel easier and smoother.