When I started following Rush Limbaugh, I was in One Way Books, a Christian bookstore, and the manager, a friend asked me to listen to a radio show, which he then turned on. As I recall it was one of those call-in shows that were popular in the 1980s. Folks would call in with comments, and the host would call them names (like stupid) and start attacking their views as uninformed or ignorant. During these verbal assaults, the mere mention of CNN, NBC, or the New York Times as anything other than leftist propaganda would make the caller's comments something that could be attacked because of its source.
I recall that his show was broadcast from Sacramento, but it may have been shortly after he moved to New York in 1988 that I first heard him.