I started listening to the JW bits of every episode in about 2004. I'd heard Rock, Rot & Rule a year or two before.
In 2010, I started listening to the new shows forward and the archives backward. With no new shows for the moment, I'm moving faster backward through the archives. I've heard enough from the early shows to know where most things are going, but the backwards thing is fascinating in that you get to hear the regular callers devolve and then disappear after you hear their first call.
Frank from Weehawken, for example, originally calls in as "Frank from Scotch Plains."