Cowell and girlfriend Lauren Silverman welcomed their baby boy, Eric, on Feb. 14, 2014, in New York City. Eric is Cowell's first child.
"The first eight to nine months I was kind of thinking, 'I don't think he likes me very much,' because babies are babies," Cowell admitted to ET. "They don't respond to you and they cry and I thought, 'Oh God, maybe he'll never like me. Then one day he started talking to me and it was, 'Oh my God!'"
Eric even has his dad's job figured out.
"I said to him the other day, 'What does Daddy do for work?'" Cowell shared. "He said, 'You press buttons.'"
Now Cowell is pressing buttons on the show he created, American's Got Talent, but there's one catch -- fellow judge Heidi Klum pushes back!
"Heidi took me a couple of days to understand what she's like and then I realized she's kind of insane," Cowell said. "She's very easy to wind up. It does remind me of me and Paula [Abdul] a little bit to be honest with you."
America's Got Talent returns to NBC with Cowell, Klum, Mel B, Howie Mandel and host Nick Cannon on May 31.