Sorry - they do not allow walk-ins at the terminal - they don't want people wandering around.
You can get a transfer bus from any 17th st hotel for about $7.00 per person.
No reservations needed - just ask at the front desk or bellman's stand outside in the morning. The leave about every 15 minutes all morning.
I am the editor, but I also speculate, ask questions and play devil's advocate. I reserve the right to change my mind.