As long as it's less than 24 hours til flight time. I confirmed my return flight from my hotel, then printed out the boarding pass at the airport kiosk. There are kiosks at the gate, too, for people who have lost their passes.

Not that it was necessary for a good seat. I had a row to myself on all my legs BLI-CMH-PSM return. Me thinks that Skybus is not long for this world.