US Airways Dividend Miles (Pre-2005 America West merger) - Checking in for a flight

I know you can check-in for a flight online 24 hours before the flight.

What is the earliest you can check-in at the ticket counter for a 10PM flight?

I know you can check-in for a flight online 24 hours before the flight.

What is the earliest you can check-in at the ticket counter for a 10PM flight?

6 hours prior.