It’s not Sheldon anymore.

The third spin-off show for The Big Bang Theory is here and it puts Sheldon’s brother Georgie (Montana Jordan) in the driver’s seat.

“I think I met them all when we started ‘Young Sheldon,'” Jordan, 21, told The Post, referring to the cast of “The Big Bang Theory.”

“Every single one of them was down-to-earth and nice people. For the most part, Jim Parsons was hands-on with Young Sheldon star Iain Armitage, making sure he understood the role. But they kind of let the countryman do whatever he wants,” he said, referring to himself.

“Georgie & Mandy’s First Marriage” premieres Thursday, October 17 (8 p.m.) and is a prequel to “The Big Bang Theory” in which Georgie and his wife Mandy (Emily Osment) are raising their baby and trying to find their way Life as young parents.

The original “The Big Bang Theory” attracted 20 million viewers when it aired from 2007 to 2019. This show followed Sheldon (Jim Parsons), a Texas-born former child prodigy turned physicist. Mayim Bialik and Kaley Cuoco starred.

Its first spin-off, Young Sheldon, aired from 2017 to 2024 and explored Sheldon’s childhood – and Georgie and Mandy both appeared as supporting characters in that series. In the original Big Bang Theory, an older version of Georgie is played by Jerry O’Connell and he runs a chain of tire shops. It was mentioned that he was married and divorced several times.

“We all know the plot is for Georgie to get married a few times, but whether it’s with Mandy the next few times we don’t know. We have to watch and find out,” Jordan said.

He added: “They could turn everything around for us. It’s a mystery to me too, I’m not entirely sure what they have in store.”

Jordan lives on a farm in Texas when he’s not acting, and much like his character, he’s a new father himself, having welcomed a daughter this year with girlfriend Jenna Weeks.

“I have a four-and-a-half-month-old child in the house,” he said.

“When you have situations that you live through in real life, it’s easier to bring them to life on TV. I guess it makes it look more natural when I hold babies on set. But I have two little nieces in real life, so I was around babies a lot.”

Even the thick Texas twang that Georgie has on screen isn’t an affectation.

“A lot of people think it’s fake, but it’s not,” Jordan said.

“I guess I was just lucky and blessed to have the start. Because the first movie I did, I was able to keep my accent,” he said, referring to the 2018 film “The Legacy of a Whitetail Deer Hunter,” starring Josh Brolin and Danny McBride.

“Then I got (the role) in ‘Young Sheldon’ and this (show), so I didn’t have a role where I had to change my accent,” he added.

Since Jordan is relatively new to acting, he said he is learning from Osment and his other co-stars.

“I think she’s just a down-to-earth person who’s easy to get along with,” he said of Osment. “She is very professional and good at what she does. I tell her all the time that I’m good at sitting on the sidelines, watching what she does and learning. I am happy to be able to accompany you on this journey. And it’s not just her. I like being a peeping Tom and just watching everyone, seeing what they do and learning from them,” he said.

Jordan and Osment dance in the opening credits of the show.

“We learned (how to dance), they brought in some people from Dancing With the Stars to teach us,” he explained.

“I think they gave us about four or five days to learn it. It wasn’t on my wish list, but if it was, I can check it off now. There’s always laughter on set.”

Regarding the possibility of becoming more famous after getting his own show since “The Big Bang Theory” franchise is popular, Jordan said, “I don’t even think about it. I don’t want this to affect my work. I just try to bring my natural self to television.”

He added: “I find that I am most grounded in Texas, so I try to get back to Texas on my farm. I try not to stay too much in the (Los Angeles) scene.”