David Letterman / Stephen Colbert CBS announced the final episode of "The Late Show With David Letterman." When Will Stephen Colbert (right) take over for the comedy icon (left)? Photo: Reuters

David Letterman, the 32-year veteran of late-night talk shows, is finally stepping down from “The Late Show” on CBS after helping create the comedy staple more than two decades ago. The network has now officially announced that his final broadcast will air Wednesday, May 20, 2015.

It’s already been confirmed that the comedy icon’s replacement will be none other than faux conservative talk-show host Stephen Colbert. Although he’ll be dropping his phenomenally popular political persona and play it straight as the second man to ever sit behind “The Late Show” desk, it’s still unclear when he’ll start.

Although the network has not announced an official date for Colbert’s first episode, he’ll be finishing up his stint on Comedy Central’s “The Colbert Report” on Dec. 18. This leaves him five months to prepare for the new gig before Letterman steps down. The only real question now is how long CBS is willing to let its flagship late-night show stay off the air?

So far, the network’s only late-night host shift has been on its “Late Late Show.” Craig Ferguson recently announced his upcoming exit from “The Late Late Show” will be on Dec. 19. The show’s new host, James Corden, won’t begin until March 9, almost three months after Ferguson leaves. However, fans of the show won’t have to go through withdrawal as the network announced a bevy of guest hosts to take over in the interim. According to Deadline, Drew Carey will bookend the guest hosts starting on Jan. 5. Additional hosts include Will Arnett, Wayne Brady, Jim Gaffigan, Billy Gardell, Sean Hayes, Thomas Lennon, John Mayer and Kunal Nayyar.

While that strategy may have worked for “The Late Late Show” when Craig Ferguson transitioned as host from Craig Kilborn in 2004, the audience for CBS’ primary talk show might not be that open to experimentation. Given that the network has yet to announce any similar guest hosts for “The Late Show,” it’s a safe bet that Colbert won’t have anyone keeping the chair warm for him.

If the trajectory of the network’s late-night rival, NBC, is any indication, it won’t make fans go too much more than a week without “The Late Show.” When Jay Leno took over “The Tonight Show” for Johnny Carson in 1992, there was only a three-day gap between their respective first and last shows. In 2009 Leno made his first messy exit from late night, and Conan O’Brien took over three days later. In a controversial move by NBC, O’Brien lost the show after only seven months, and Leno resumed the hosting role again after 10 days. The longest gap between late- night hosts for the peacock network was between Leno and current “Tonight Show” host Jimmy Fallon – only 11 days. While it’s not necessarily fair to hold one network to another’s standards, it’s clear that the general thinking on the matter is to not make fans wait too long between hosts.

This could put Colbert’s first episode sometime in late May or early June. However, nothing is certain until CBS makes its formal announcement. In the meantime, fans can only soak up the remaining five months with David Letterman.