Originally Posted by
San Gottardo
As I land at JFK already today on another flight, can I already go to the AA counter there and get a boarding pass for tomorrow morning? It would be 18 hours before departure. Online check-in opens 24 hours before departure, what about check-in at the counter? I have no luggage to check.
Yes, as long as you're within 24 hours of the flight they can check you in at the airport counters, even if it's the day before.
I've done this a few times at various airports over the years.