For me, I applied only to one school (early decision). When they realized they wanted to interview me, I was sent an email. The emails stated the wanted to interview me, gave the date/time/general information, then they wanted me to confirm back (through phone or email). I went to the interview, which was about six hours.... interview, campus tour, information, free lunch, etc. They notified me within 10 days of acceptance. This was early decision so the process was quite fast for me, it could be much longer with different schools and regular admission status. Irregardless, however; I would recommend applying as eary as possible for your best chances of being accepted.