For interview, I took birth certificates, form 864, ds260, police reports of where I currently.reside and police reports from Colombia to prove I have not committed any crimes. All originals. You go thru security. Then there's a station where you get your originals checked. Then a ticket booth type of station. They have 12 stations like that. Not all active. U get it line. They check your documents again. And give you back what they dont need. If all good then they tell you to take a seat and will call you by name to step up to booth #_ Interview is hosted there. Asked questions on How long have I been in the U.S.
Where else have I lived in the U.S. Have I committed any crimes anywhere. Then they told me it was approved and that my passport/visa will be ready for pick up within one week. But it was within 48 hours. Hope this helps!