Not many young actors make their professional stage debuts in New York. Fewer still make them as Stark Sands did — in an acclaimed Broadway revival, in this case of R.C. Sherriff’s 1929 World War I drama, “Journey’s End,” amid one of the most talented ensemble casts in recent memory. And it’s a tiny minority that cap their first Broadway run as Mr. Sands has — with a Tony nomination, for best performance by a featured actor in a play.

The heady success enjoyed by Mr. Sands, 28, is all the more surprising given the fact that six months ago, he was another Los Angeles actor auditioning for television pilots.

What a difference six months make.

On Sunday afternoon, hours before the Tony Awards begin, “Journey’s End” will have its final performance. On Monday, Mr. Sands will fly to Africa, where he will spend the next seven months filming a leading role in “Generation Kill,” an HBO Films miniseries based on Evan Wright’s book about the first month of the 2003 Iraq invasion, from the creators of “The Wire.”

“Sunday’s going to be a crazy day,” Mr. Sands said last week, sitting in a NoLIta café not far from his apartment. “We close the show that day. I’ll finish the show, go upstairs, shower, jump in a tux, jump in a town car, and go do a red carpet. And then I’ll sit in the Tony Awards.”

At the thought, he couldn’t help but smile, and when he did, the resemblance to his “Journey’s End” character — the fresh-faced, earnest, sandy-haired Lieutenant Raleigh — was unmistakable. It was easy to see how a casting director could have envisioned Mr. Sands, whose biggest prior credit was a minor role as a soldier in “Flags of Our Fathers,” as Raleigh, the green recruit among the hardened regulars.

He was living in Los Angeles when the call came last fall from a casting director — one of those, “If you’re going to be in New York, we’d love to see you” calls. Mr. Sands made sure he was in New York. At the first audition, he recalled, he “could do no wrong.” Three weeks later, the phone rang again, with an offer to fly him out for the callback. In a grueling 45-minute second audition, director David Grindley put him forcefully through his paces. A few days later, he had the job.

Once he was cast, Mr. Stark found himself the real-life novice among veterans. He arrived at the first rehearsal with all his lines memorized. “I was nervous, because I was the new guy, and I didn’t want to be underprepared — which worked, because that’s who Raleigh is,” Mr. Sands said. “And we really did become a group. I mean, Boyd [Gaines] is like my uncle now.”

The men who make their home in the “Journey’s End” bunker — Mr. Sands, Mr. Gaines (a Tony Award nominee for best actor in a play), Hugh Dancy, Jefferson Mays, John Ahlin, and Justin Blanchard — bonded under the influence of the demanding Mr. Gridley. At times, Mr. Sands said, he felt himself resisting the specific, meticulous direction.

“Then we got in the theater, and the audience validated everything that he had told me, all those little moments he wanted to be just so. And I discovered that I could still find my own way of doing it within his boundaries.”

Perhaps his most difficult scene is his onstage death at the play’s end, a wrenching emotional scene that nonetheless poses significant technical challenges, like keeping his legs still while moving his back. “It’s a weird thing to try to be in the moment while thinking about getting gradually quieter and not moving your legs and not being able to breathe,” he said.

Mr. Sands hails from Dallas, and his mother will fly up from Texas to attend the Tony ceremony with him, along with a passel of relatives coming to see the show. (His father died of cancer in 2003.)

In the meantime, he has been on the busy schedule of luncheons and press appearances that are de rigueur for the nominated. “I walked up to Angela Lansbury at an event and actually had the guts to tap her on the shoulder and introduce myself,” Mr. Sands recalled. “And before I could tell her who I was, she said, ‘You’re Stark Sands from ‘Journey’s End.’ It’s so backwards. It’s like living in a dream.”

Mr. Sands’s dream has kept him working six days a week since January 8, when he started rehearsals for “Journey’s End.” Going directly from “Journey’s End” to his Africa shoot, he estimates he will not return to his apartment in Los Angeles for a full calendar year. When he does get back, he plans to relocate to New York.

“This is where I’d like to live,” Mr. Sands said. “And the opportunity to do more theater is very appetizing.” In five of his last six jobs, he has played soldiers, but he is eager to show the range he displayed in earlier projects like the Charles Busch film “Die, Mommy, Die!” where he played an obsessive-compulsive cross-dresser, and in Broadway’s recent Easter Bonnet Competition, where he and his castmates took first place with a “Jersey Boys”-like song-and-dance parody of “Journey’s End.” “The audience was three times the size of ours, and when we finished, this enormous tidal wave of sound just blew me away,” he said with a grin, looking every inch the green young recruit from Dallas. “I would love to do a musical in this town.”