Chad Batka / New York Times News ServiceJohn Oliver, known for his appearances on “The Daily Show,” debuts his own comedic news-commentary show, “Last Week Tonight,” tonight on HBO.

Felicitous timing has powered the steeply ascendant television career of John Oliver since the day he landed in New York from London — July 16, 2006 — and, just 24 hours later, sweaty and jet-lagged, found himself mocking Tony Blair in an exchange with Jon Stewart on “The Daily Show.”

“George Bush had said this ‘Yo, Blair’ thing at the G-8 Summit and then had this whole conversation with food in his mouth,” Oliver recalled. As the sole British writer on the show’s staff, he was thrust onstage to joust with Stewart on his satirical Comedy Central newscast, playing the role of “Senior British Correspondent.”

“I was thinking: ‘OK I’m tired, it’s hot here, I’m sure they’ll just let me get my feet on the ground,” he said. “Instead they said: ‘Write a piece; it’s on the air tonight.’ It all went by in a blur.”

After that blur came popularity and admiring reviews, and now Oliver, 36, catapulted into the top rank of late-night comics, is about to kick off his own late-night satirical news show tonight on HBO.

But about that timing …

The show, “Last Week Tonight” at 11 p.m., begins only weeks after a sweeping upheaval in late-night television that opened up some of the most prominent host chairs in the business, including David Letterman’s at CBS and, subsequently, Stephen Colbert’s at Comedy Central. “It’s like tectonics,” Oliver said. “It looks like everything is still, and then everything moves and there’s an earthquake.”

Before he accepted the HBO job, Oliver, riding the wave of a three-month stint subbing for Stewart last summer, had fielded a surge of offers. CBS dangled a possible shot at the 12:35 a.m. slot following Letterman. Had he accepted, Oliver might have already been in position to slide up to the big chair. More logically, had the late-night earthquake hit a few months earlier, with Colbert signing with CBS, Oliver would have been the presumed heir on Comedy Central.

“Last Week Tonight” will be a comedic commentary on the news of the week, not the day. It will not be a faux newscast, Oliver said, and will not consistently skewer cable news, as “The Daily Show” does.

Two test shows gave him a taste of what he might do, but it may take time to fall into the rhythm of a weekly show. “We can’t repeat what the other shows have done during the week,” Oliver said. “We do get a free shot at the Sunday morning shows.” Looking ahead, he spotted the elections in India, which continue until mid-May. “No one else is racing to do that story,” he said.

The show will be a half-hour, but a legit half-hour — no commercials. That will allow for longer pieces. Oliver was still unsure whether the format would routinely include a guest.

“I like the idea of carving out my own space, rather than having to step into some difficult shoes,” he said.

He had the shoe experience during Stewart’s sabbatical from anchoring “The Daily Show,” a role that had vaulted the host to the status of champion of truth-telling about the news and media.

Stewart, who took the time off to direct a film, said he looked to Oliver and his “real dexterity” to keep “The Daily Show” running with the least disruption. “Put a guy in to do exactly what I would do — with a much better accent so that there would be a Dickensian quality, a show hosted by a very smart orphan.”

The experience turned into far more fun than Oliver anticipated, although it began with exactly the level of terror he had feared. “There are about 7 seconds when that music plays at the top of the show, 7 seconds for your heart to burst out of your chest,” he recalled. “I sat there thinking: ‘Is this visible? Can you see a heart in a chest? No, that’s a cartoon.’”

Nobody noticed. Instead, reviews bordered on rapturous.

Among the highlights of his ensuing career at “The Daily Show, probably the most memorable for him was covering the 2008 Republican Convention in St. Paul, Minn. As his usual obnoxious correspondent, he was at risk because he could not afford to get arrested for anything — deportation loomed. So when he wandered into a restricted area and was pursued by security, he sought refuge among some veterans invited by pro-military politicians. The one who helped Oliver hide out was a female vet, Kate Norley. He was grateful, took down her email and married her three years later. (He is still a British citizen.)

Notably, as Oliver gets his shot to score, the playing field is surprisingly open. On Sunday night at 11, he will be the only late-night comic at work.

Oliver will do 25 shows in a shortened season, then move to 35 (the same number Bill Maher does for HBO). Another bout of terror may set in when Oliver tapes the show for the first time. But he will be seeking help in the best place he knows.

“I ask Jon for advice regularly,” he said.