ok so heres my experience.
i had my interview at 9.30am,, and i wnt inside the buliding before (if u say ure on the k1 visa it is allow). the time between my arrival and the actual interview was 4Hr aprox.
the lady was nice. shes asked me:
whats the name of your gf
when was the last time u too saw each other.
how long have u been dating her
what are your wedding plans
and thats it
congrats!!
ur visa wil arrive in aout 2 weeks