The siblings of The Band Perry weather fame together

When a band of twentysomethings suddenly becomes immensely popular, the usual reaction is to deem them an overnight success. The Band Perry seems to fit the description, having taken Nashville by storm in 2010 with a hail of hit singles and a million-selling album.

But the three siblings — Kimberly, 28, Reid, 25, and Neil, 23 — have been in the music business for 14 years, with the brothers getting their start in show business by being grade-school roadies for their sister’s band. They formed a trio 10 years ago.

So they were veterans by the time they were discovered in 2008, and that experience was crucial when their world exploded two years ago with the success “If I Die Young,” the first of the band’s four Top 10 singles.

“We wouldn’t have given any of that up for the world, because we learned so much,” said Reid Perry, the band’s bassist. “Like learning how to cover up mistakes that we made on those smaller stages instead of having to do that on an awards show, or in Louisville.”

“I agree with Reid,” said Kimberly Perry. “That time was invaluable, and it was always important for us to not grow up in front of the world. We wanted to be somewhat unseen while we were figuring out what our music and our creative voices were going to be.”

The Band Perry closes the 2012 Kentucky State Fair with a show Sunday night in Freedom Hall. Moving from clubs to opening for Tim McGraw to headlining arenas has been a journey they’ve embraced since their childhood in Alabama.

They’ve often said in interviews that a career making music has been their sole focus, but even so, the speed with which everything changed was startling. No matter how much experience they gained as teens and young adults, nothing could have prepared them for such a bright spotlight.

“Since our first song came out on the radio two years ago, everything has moved so quickly that I feel like in some respects we’re really growing up in the moment,” Kimberly Perry said. “An occasion arises, and then you have to rise to it. It’s been a hard transition from opening act to headliner. You go from playing 35 minutes to 75, so we’re figuring out how to keep folks entertained when we’ve only had five singles on the radio.”

“We love the smaller venues because there’s more banter with the crowds,” said Neil Perry. “It’s kind of a science learning how to play all of these different venues.”

In case you hadn’t noticed, The Band Perry does interviews as a group. Although part of their seamless interplay is no doubt from practice, there’s definitely a familiarity that only comes from blood relatives. But while one might often finish the other’s thought, you quickly get the sense that the last word often goes to big sister.

“In our family there’s an ongoing debate about whether I’m the boss or just bossy,” Kimberly said. “It’s amazing how one letter can make all the difference. But we really do man the stereotypical roles. I like to keep a firm grip on the steering wheel as the oldest — and the one girl.”

“And as the youngest, I’m the one to cause all of the trouble and keep everyone laughing on the road,” Neil said.

“And then we have the middle child,” Kimberly said.

“And everything that goes along with that,” Reid said. “Mainly being the peacekeeper.”

“And getting away with everything,” Kimberly said. “Really, though, we know each other very well, and we all bring something distinctive to the table.”

Nothing will test a band’s patience like a few weeks cramped up on a tour bus, but the members of The Band Perry said they keep things civil in part because of some good parental advice.

“Our parents raised us to be a unit,” Kimberly said. “I remember when we were kids, they took all three of us over to the window — we’d been in some little spat — and they said, ‘There’s a big world out there, and you’re gonna have to fight in it every day, but you’re not gonna do it in our household.’

“So much of that comes in handy now. The three of us are like The Avengers. We really man up and support each other.”

The Band Perry is finishing work on its second album, which it’s making with producer Rick Rubin. Rubin, who got his start in early hip-hop, has become one of the biggest producers in rock. He also helped the late Johnny Cash make a comeback with a series of very good albums made during the legend’s last few years. The Perrys said that Rubin was extremely hands-on and an active participant, which belies his reputation as being more of a Zen master.

“The one thing we knew about Rick, and the reason we were so keen on working with him, is that unlike anyone else, he has a way of helping an artist reach inside and be their very best,” Kimberly said. “He’s about challenging the artist to write their best songs and perform their best on tape, and he’s certainly been that guy for The Band Perry.”