I hate to tell you; but the wait can be anything from very brief to the entire cycle. I got an interview at KCOM and UHSCOM within 2 weeks of sedning in my secondaries. On the other hand, I applied to Johns Hopkins in July and was placed on 'hold for interview' status until I was finally rejected in like late March or April.
Sorry I couldn't be any more enlightening!
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'Old Man Dave'
KCOM, Class of '03