Joshua Turchin’s gotten around. He sang as Flounder in a live performance of “The Little Mermaid” at the Hollywood Bowl, toured with the musical “A Christmas Story” and lent his voice to several animated films.

It was only a matter of time before the actor/singer/dancer/pianist wrote his own musical: “The Perfect Fit,” opening Sunday at the Rave Theater Festival.

Josh is 12 years old.

“I was bitten by the theater bug from a very, very young age,” he tells The Post in his high-pitched voice. Just weeks after the family moved to New York from Fort Lauderdale, Fla., Josh, then 8, signed with an agent and booked a job. He’s hardly stopped working since.

His parents, Jason and Kira, were always supportive. Not even the premature birth of her daughter, Shaina, kept Kira from taking then-2-year-old Josh to a local production of “Grease.”

“We didn’t want to let him down,” she says. “I left the hospital after two days and took him to the play.”

‘I was bitten by the theater bug from a very, very young age.’

At 6, Josh saw “Once” and suddenly knew what he wanted to do.

“I looked over at him and tears were coming down his face,” says Kira. “I’m like, ‘What’s wrong?’ He looked at me and said, ‘This is the most beautiful music I’ve ever heard.’ ”

From then on, he wanted to be a composer, like his idol, Disney’s go-to songwriter Alan Menken.

Josh’s first idea for a musical — one based on a horror video game called “Five Nights at Freddy’s” — didn’t pan out, because he couldn’t get the rights to it. (He was 9 at the time.)

“I spent the next year trying to figure out what I was going to write about,” he says. “Then my mom said, ‘Why don’t you just write about your life?’ ” Josh buckled down and got to work.

“The Perfect Fit” is about a teenage actress struggling with her age: She’s too young to play an adult and too old to play a child. Josh, who’s also in the show, says he wants to see more age-appropriate casting on Broadway and off.

For now, he’s focused on being in charge of a musical without “sounding mean.”

“I just need to make sure that I trust those people [I’m working with] and that I always have to be nice,” he says. “Being friendly, listening . . . always gets me through the day.”

“The Perfect Fit” plays Sunday through Aug. 23. Teatro LaTea Theatre, 107 Suffolk St.