Sugarland, Jason Aldean + More Talk Pivotal Career Moments

Was it the first time they were asked for an autograph? The first time they won an award, or heard their song on the radio? Or maybe it was the first time they got to meet Bert and Ernie! Ask any celebrity the moment they knew they'd made it in show business, and you're bound to get a very different answer from each one. 'Entertainment Tonight' host Nancy O'Dell did just that on the ACM Awards red carpet and shares with The Boot these 'The Moment I Knew' video clips from Sugarland, Nicole Kidman, Jason Aldean, Lady Antebellum, Luke Bryan, Hunter Hayes and Steve Martin. Click on each thumbnail below to watch the videos.