Ok serious ques about auditions...tv...?

Ok I have a question or a couple. I live in NYC..and I'm aware that when you want to be on a show like American Idol, Project Runway, or On the Lot or etc.. you are supposed to just go out and audition. i was wondering though how would i know before the auditions even happen? if they made an acting show or something im really interested in... something like project runway..or On the Lot how would i find out about when the auditions are? where would i look? thanks in advance...serious answers only PLEASE