Sometimes, immediacy is the mother of invention.

That certainly seems to have been the case for “Killing Kennedy,” the adaptation of the Bill O’Reilly-Martin Dugard bestseller that is premiering Nov. 10 on the National Geographic Channel.

At the film’s Saban Theatre premiere celebration Monday, a common touchstone was the film’s 18-day shoot, a sprint through the layers of circumstances that brought John F. Kennedy and Lee Harvey Oswald to their fateful intersection, 50 years ago this month.

“On the first day, I think I did the Bay of Pigs, the Cuban Missile Crisis and interns in the pool,” said Rob Lowe, who played JFK. “The first day would have been four weeks in a Bob Zemeckis movie.”

Jack Nosewothy (pictured above, with co-stars Will Rothhaar and Michelle Trachtenberg and director Nelson McCormick) played Bobby Kennedy and said the emotional wreckage of hearing his onscreen brother had been shot came on his very first shot of his very first day.

“We did it in three takes, and I think they used the first,” said Noseworthy, who added that he learned that scene would be his starting point the morning before.

Of the 18 days, the first eight were spent on the Kennedy scenes and then the final 10 centered on Lee Harvey Oswald, according to the man who played him, Will Rothhaar. Doing 13 scenes in a day’s work wasn’t unusual, he said.

With Virginia the location for the film’s entire production, including the re-creation of Minsk, where Oswald met his wife Marina (Trachtenberg), fast adjustments were par for the course. Rothhaar portrayed the American expatriate, layered in clothes and shivering, while it was “94 degrees outside with 100% humidity.”

The actor added that his goal was to find the third dimension in Oswald.

“Talking to my dad one night in Richmond, I just was reflecting how grateful I was raised in a home where love was never spared,” Rothhaar said, “and I started thinking about Oswald’s upbringing. Once I realized he never had that growing up, I felt this overwhelming sense of sadness. I got him. … Instead of looking at his eyes, I was looking through them.”

Calling it “a global television event on an indie film budget,” NGC prexy Howard T. Owens introduced the film – and Lowe – with great enthusiasm.

“We are evolving into a network that makes huge, culturally relevant television,” Owens said.

“The easiest decision we had was deciding who we wanted to play Kennedy,” he added. “I sat staring at Rob, my man crush in full bloom, calculating how we were going to get Rob to play this role. When Rob agreed to play JFK, he elevated the status of this network.”