Our appointment is at 930am. We arrived at about 9am. The gentleman in front was nice. He wanted to make sure we got either confirmation of DS260 or the P4 interview letter. He handed us the number before my parents went in. No bags allowed. He also told us to make sure my parents went upstairs and sit in the middle of the room.
I didn't go in. My parents said they first check all the documents. It took them a while. Then it's the interview. The questions were very general.
They came out a little after 12. Everything went smooth!