As the title of her album suggests, "The Day Has Come" for 15-year-old Cheyenne Kimball. That may seem like a bold statement from someone so young, but she worked on her Epic/Daylight debut for more t

As the title of her album suggests, "The Day Has Come" for 15-year-old Cheyenne Kimball.

That may seem like a bold statement from someone so young, but she worked on her Epic/Daylight debut for more than three years, and the last year of the process was filmed for the MTV reality show "Cheyenne."

That early exposure has given Kimball's music a big boost. This week, "The Day Has Come" enters the Billboard 200 at No. 15, while the lead single and theme song from the show, "Hanging On," is No. 53 on the Billboard Hot 100.

"I'm on top of the world," Kimball tells Billboard.com. "I just found out that on iTunes my album is like the No. 1 selling pop album, and No. 5 overall of every album sold. My first week and I'm already No. 1? That's unreal."

Unreal but not totally unexpected, considering the popularity of her show. "I had an idea that it would help, but I had no idea that it would help this much," she notes.

Kimball's newfound fame means that she won't be doing all the normal things that teenagers get to do, but she's more than happy to have that problem.

"I've been able to do so many amazing things, so it's like I don't really like need high school or anything," she says, adding, "I can't go anywhere right now without getting recognized. I was walking out of my hotel today, and I had sunglasses on, wet hair, no makeup -- I don't know how anybody could ever recognize me -- and this girl like screams from across the street, 'Cheyenne!' She runs up to me and is like, 'I knew it was you. I knew it, I knew it, I knew it!' It's really amazing, and so cool that somebody is that happy to meet me, you know?"

Moments like these are what Kimball has been dreaming about since age 8, when she began writing songs. In fact, by the time she was 12 she had written close to 200 songs and was crowned "America's Most Talented Kid" on the NBC TV show of the name. But it was an appearance on the "Today" show that nabbed her a record deal.

"Sony's head of global A&R, David Massey, saw me on the 'Today' show giving an interview before I had even won," she says. "He had no idea I was a musician. He was on the treadmill watching TV on mute and he just saw how poised I was for 12 and was like, 'I need to find that girl!' "

She was signed soon after, and began working on her album right away. Although she had hundreds of songs under her belt, she scrapped everything and collaborated with such songwriting heavy hitters as Billy Mann (Joss Stone, Teddy Geiger) and Kara DioGuardi (Ashlee Simpson, Lindsay Lohan).

"I started completely fresh," she says, adding that she wanted her songs to have a timeless quality. "My lyrics are not age based. If anything, I write a lot older than my age. Maybe I could outgrow them when I'm a little more mature, but they are always going to be the songs that introduced me to the world."

One thing on the album that Kimball has already outgrown, though, is her vocal range.

"My voice changed," she says. "My voice is a lot higher on the album than it is now. I thought about rerecording it, but we were already too far in, the album was about to be released. Plus, I didn't want to completely erase all the work that I've done over the years."

Now that her day has indeed finally come, Kimball is already looking ahead, but she's not sure if a second season to her show is in her future.

"I'll be traveling out of the country and it's just too hard for [MTV] to film out of the country, and I really want to focus on touring right now," she says.

Either way, the experience has been a positive one, and she's been able to prove the naysayers wrong.

"If [people] really think I'm manufactured because I'm on MTV, that's OK. I'm not, and I know that and that's really all that matters," she says. "I'm just gonna keep playing my music and do what I do, and hopefully people will understand that I'm just in this for the music. I didn't do it for fame, I didn't do it far any of that. I just wanna be able to play arenas one day."