Went to my 8:15 appointment at IAD today. Of note is that that the entrance door says the office doesn't open until 10 am, but CBP officer arrived around 8. Waiting room had a sign on the wall saying no walk-in appointments. All people in the waiting room had appointments for this morning except possibly for one spouse.
While taking the passports for two couples, the CBP officer made it sound like she only needed one of them to have an appointment today so spousal/family walk-ins definitely sound possible at IAD. Unfortunately, I cannot comment on straight-up walk-ins.
Last edited by el_bajo; Jul 7, 2016 at 9:39 pm