I had a similar situation. I had called the shuttle system from the airport in the morning right before the interview (they are open 24 hours, I believe). I arranged to be picked up around 3:15, and the driver even came ten minutes early. My interview even ran late (I was the last one to finish my writing sample too). I wouldn't recommend the bus -- you never know what could happen, alot of stops, etc. The shuttle is more expensive (twenty bucks) but I got there with plenty of time to spare. Hope that helps.