In January, Jon Stewart's taking over hosting duties on Comedy Central's The Daily Show, so during a conference call a reporter makes him play "Five Questions", the program's segment that submits celebrities to goofy queries.

A sample: "Who's the better late-night host - Larry Sanders or David Letterman?" Stewart appeared as himself on and wrote for Garry Shandling's late night Sanders parody, and once had a development deal with Letterman for a late-night talk show. He thinks carefully. "Sanders had his day," he says, "but Letterman is forever."

Ironically, the one question Stewart can't answer is how The Daily Show will change when he replaces smarmy Craig Kilborn as host. Stewart reports to work Jan. 4; his first show airs Jan. 11.

"What I learned from doing my late night show is that you can't plan this kind of show in advance," says Stewart, 35, who'll appear as a guest on The Daily Show at 11 p.m. today. "We spent four months designing that show, and the first week we were on the air it was evident that 75 percent of the stuff we thought would work didn't. "The news is the currency of The Daily Show. I can't write a show on Jan. 4 and run it on Jan. 11. You've got to write it on Jan. 11."

Kilborn, whose final Daily Show airs Thursday, is headed to CBS to take over The Late Late Show from Tom Snyder. Stewart, ever the bridesmaid, had also been up for that job, just as he once lost the chance to host a post-Letterman Late Night to Conan O'Brien. He says he doesn't agonize over such missed opportunities: "As long as I don't end up hosting a skin care commercial with Cher, I'm happy."