"As the only man alive who's hosted The Tonight Show & Late Night, I want to congratulate @JimmyFallon & @SethMeyers. They'll both do great!" the 50-year-old Conan host wrote on Monday, Feb. 17. (Meyers, a fellow Saturday Night Live alum, is set to take over Fallon's spot as Late Night's host on Feb. 24.)
O'Brien was referring to his short-lived (but much-publicized) stint as host of The Tonight Show back in 2009. After O'Brien replaced Jay Leno during his first retirement (and flew his entire staff to L.A.), late night's favorite redhead was famously pushed out so Leno, 63, could take the job back. Leno went on to host the legendary program for five more years, and finally handed over the torch to Fallon -- presumably for good -- after his final episode on Feb. 6.
As for Fallon, his debut has finally arrived. Hours before his first curtain call, the 39-year-old host wrote a heartfelt message via Instagram alongside an image of his new Tonight Show logo.
"February 17, 2014 This is it. We are starting a new chapter of the Tonight Show. I can't even begin to describe what we are all feeling right now here at 30 Rockefeller Plaza, NYC," Fallon wrote. "But - I know that we'll never have this exact feeling ever again. By this time tomorrow we'll no longer wonder what it would be like to do the Tonight Show. We can't put that feeling - that moment back in the bottle."
"All we can do is try to make the best show that we can and make people happy," he continued. "And we will. Here's to the first of many. Fun."