KELLY CLARKSON has long said she couldn’t wait to start a family – and it looks like she didn’t even wait for her wedding to get pregnant!

The first “American Idol” champ seemed to be sporting a noticeable baby bump while performing in New York City on Oct. 10.

“She said she wanted babies right away after getting married, and it looks like she jumped the gun,” noted an in­sider. “She’s already picking out names.”

The Grammy-winning singer is set to wed beau Brandon Blackstock at the end of the month. He’s the 36-year-old son of Kelly’s longtime manager Narvel Blackstock and stepson of country legend Reba McEntire.

The two have been dating since last year, and Kelly has already shot down rumors she was pregnant once. That happened in August after she mentioned her plans to elope instead of having a traditional wedding.

Meanwhile, Kelly, 31, has been living with Brandon and his two children from a previous marriage, and she said in a recent interview: “I can’t wait to start to have babies with him.”

While Kelly has already picked out two possible names for a boy and two for a girl, she predicted: “I’m totally gonna have a girl. I know it in my soul.”

She’s even watching what she eats, saying: “I want to do the best I can for that kid…right off the bat.”