Here is my experience of same day interview and oath in Seattle.
Interview
My interview was at 9:00 but I left early (6:30) since I live 30 miles away and traffic is a nightmare around there. I was lucky to bypass two bad crashes because I was listening to the radio and got to a Starbucks near there for breakfast.
I went there at 7, just in case 1 hour earlier. Office opens officially at 7:30, but security let me in. The office is on 4th floor, but they let me in because we had 4 month old baby. So durin security check you are checked like in airport, I took off shoes and family members too.
We went and there is reception and I checked in my additional evidence.
I think it will be different with each people. In my case, all three times were different.
The officer usually did a small talk with me while going to the room from the hall asking me about the weather and other information which was not listed in application from my previous state where I lived and how I liked it here. IMO, I took that in good and bad way. Good way in the sense, that he wanted me to feel comfortable and bad way, like as if he is saying, I already know everything about you. So, its a mixed bag.
This week I went for my oath ceremony and I am now officially a US Citizen.
The process was very smooth overall.
My only beef is that for the interview I had to go to Holtsville and for the oath I had to go to Central Islip. I live in Queens and I don't drive so getting to those places was a major issue.
Here's my N400 timetable:
Queens/NY
5 years rule
I had my N400 interview last week. I passed the English questions without an issue.
Quick background: I was issued 10 year bar and deported in 2005. I had to apply for I601 and I212 (waivers) prior to returning to US. The reason I was deported was because I had overstay after deportation order. I returned to US 2010.