I would like to chime in on this topic.
I arrived at ATL today with a person from the tower waiting to pick me up and take me over there to listen in for a while. He has been a family friend and controller for a very long time. I was able to plug in at about four positions (they were running all 5 runways, per normal) , and was able to talk with, and listen to probably seven different controllers. Some were veterans of 15+ years, and two of the people were only there for three months (they were the most fun as they were closer to my age).
There was one common question that came out of every single one of their mouths, "are you wanting to come here after OKC, if you make it through?" My response was, "not a chance." They, every single one of them, said pretty much the exact same thing, "that is the smartest thing I have heard someone say in quite some time."
Just from that response, it really does show that people should start early. They said that new controllers that get sent to ATL, LGA, ORD, ect., get thrown to the wolves right off the bat. If they can handle it, which most don't seem to be able to, good for them, but those people are very few and far between.
Needless to say, I did get to see some cool stuff. Right as the departure push was happening, they had to switch runways due to wind. It was quite a sight to see 12+ lined up for one runway, then another 10 starting to lineup for the other, and with some crafty work by the controller I was watching, the 12+ that had to change, got out with very little delay. That was by one of the newer controllers, but then again, he was former air force controller.