Here's a copy of an Associated Press report from 2005 containing the claim that WINS originated the term in 1972 (although other sources have said 1965) but that the specifics were lost to history:
http://www.yehoodi.com/comment/73943/1010wins-is-40
Some articles on the possible origination of the "22 minutes..." phrase;
most seem to point to a marketing consultation where the number "22" was deemed to be "most memorable" from an advertising + slogan standpoint:
Ex-KFWB newsman Don Herbert recollects (taken from his book out at the time in 2006): http://articles.latimes.com/2006/jun/16/local/me-only16
WINS News Director Ben Mevorach recalls (from 2013): http://helpthe99ers.blogspot.com/2013/03/you-give-us-22-minutes.html
October 28, 1973 New York Magazine ad for 1010 WINS - earliest ad mention I could find for the "22 minutes..." slogan:
https://books.google.com/books?id=2...wins"&pg=PA78#v=onepage&q="1010 wins"&f=false