I tried to do my interview at the SEA or SFO office, but both were booked way in advance. I also had a MIA trip coming up and checked for MIA. their whole calendar was pretty much empty and the officer told me that I dont even have to make an appointment at MIA I can just walk in. Well thats what he told me. He is also the one who told me to use my VISA page instead of passport ID page to get scanned at the booth. Luckily I figured that out myself before going back in line and waiting for ever in the regular immigration line...