The "Hail Caesar!" star landed one of the most sought-after parts in the industry in July - apparently beating out stars like Taron Egerton and Jack Reynor.
The 26-year-old is in London preparing to shoot the new film and he said the road to his casting was a long one, reported Contactmusic.
"I had an audition process that went on for a long time and I got to spend a lot of time with the guys who are directing the film," he said.
"It was pretty fun because I enjoyed the material a lot. Last year I read for the directors, then came to England and did a test on the Falcon, then came back and did a couple more screen tests in Los Angeles.