I485 interview

I was schedualed to have an I485 interview next week. I am wondering how long this interview will usually last? Can I finish this interview within 3 hours? Since I would have another important meeting on the same day. If I485 interview lasts more than three hours, I would have to reschedual my meeting in the afternoon? By the way, I will have my interview at NYC local office. If someone had this kind of inerview before, please tell me how long your interview took. Thanks very much.