Anatomy of the David Letterman News Break: How It All Went Down, Step By Step

April 3, 1:03 p.m. (PT): R.E.M. bassist Mike Mills, performing on Thursday night's edition of "Late Show with David Letterman," sends out this Tweet to his approximately 1300 followers:

1:05 p.m.: TV Guide Magazine's Rob Moynihan, a big R.E.M. fan and likely the only TV reporter among Mills' small group of followers, sees the Tweet -- and checks Mills' Twitter feed. He sees that Mills had earlier Tweeted about his guest stint on Letterman that night, and suspects that Mills really is Tweeting about Dave's retirement:

1:10 p.m.: I see Rob's Tweet, and immediately suspected that big news was indeed upon us:

1:10ish p.m.: CNN's Brian Stelter sees Rob's Tweet also, and retweets it. Stelter has more than 200,000 followers, so once he does so, the news is out there. Everyone is off and running.

1:19 p.m.: Stelter confirms the news on his Twitter account:

1:40 p.m.: Everyone frantically calls CBS and Letterman's camp, but they're not responding yet. Perhaps thrown for a bit of a loop by Mills' Tweet, although it was clear they'd be putting the news out soon anyway. So it takes until 1:40 for Deadline to send out their news alert:

1:40 p.m.: Also by then, the radio interview requests start coming in (I eventually spoke to KNX Los Angeles, WTOP Washington and KFBK Sacramento on Thursday):

1:45 p.m.: Deadline sends out a second news alert.

1:47 p.m.: Variety's news alert goes out.

1:50 p.m.: The Hollywood Reporter's news alert arrives.

1:50 p.m.: Letterman's press relations firm makes it official:

2:14 p.m.: CBS follows up with their own statement.

2:30 p.m.: Barely an hour after the news was confirmed, Letterman analysis pieces already start posting, including this smart one by Brian Lowry:

2:40 p.m.: The body's barely cold, but speculation -- including some outlandish choices -- about post-Letterman scenarios are already everywhere:

4:45 p.m.: Letterman releases the full nearly 10 minute video from that night's show where he announces his retirement. Every news site quickly reposts.

5:05 p.m.: By early evening, sites have already put together slide shows and other clicky clicks on the future of CBS' "Late Show":

Also by early evening, Letterman's YouTube channel posts this backstage interview with Mike Mills on how he broke the news:

7:25 p.m.: Even Los Angeles Mayor Eric Garcetti is getting into the act, asking CBS to move the new "Late Show" to Los Angeles. Keep in mind, this news is just six hours old.

9:30 p.m.: By now, it's already on to David Letterman career retrospectives. He's still doing the show for another year, but looks like this will be The Longest Goodbye.

10:12 p.m.: Mike Mills is strangely getting into Twitter fights with people who thought the musician ruined Letterman's announcement. (Mills points out that the audience of 300 would have spilled the beans awfully quick anyway.)

Postscript: Mills now has 2,890 followers (and counting) -- having added around 1500 in the past day.