Depend on each school. Most schools organize interviews in batches. They'll call or send out acceptances in the same day. If your interview day is at the end of the batch, you don't have to wait long. Like at NSUCOM, I only waited for 2-3 days after the interview. For other schools, I waited about 2 weeks. Notice, my interviews were from Nov to Feb. If you have an interview in Aug-Sept, you may wait longer because they start to send out the first batch of acceptances in mid-Oct (if I'm not mistaken).