The 54-year-old actor took his and wife Caitlin McHugh's 4-month-old son to meet the cast and crew of the Netflix series for the first time earlier this week. ET's Lauren Zima was also on the famous set, where she chatted with Candace Cameron Bure, Jodie Sweetin and Andrea Barber, who couldn't help but gush about their Uncle Jesse's little man.
"We all got to meet Billy," Bure shared. "I did not want to let him go... I wanted eat him, you can't give him back! He was just the perfect size."
Sweetin, who was over the moon about meeting Billy, added, "We're very excited aunties." The moment was definitely sweet for the actresses, who grew up with Stamos on the original Full House series and have gone through many stages of their lives together.
"To get to see him with [a baby], it's great," Bure marveled. Meanwhile, Barber said she always knew that Stamos "had the magic touch with kids."
'Fuller House' Star Candace Cameron Bure Calls John Stamos a 'Baby Whisperer' (Exclusive)
As for Stamos, the new dad thought it was "just the perfect timing" to bring his son on set.
"Everybody was here… He's old enough to bring around," he told ET, adding that it was really his wife, who was also on set, who pushed him to introduce Billy to everyone.
"I was sort of nervous about it because it was a big moment. She's like, 'It doesn't matter,'" he said. "I go, 'It does matter. This is an important moment. I've known these people for 30 years. I've talked about having kids and now I brought mine on.'"
When the moment did come, the new dad confessed to getting emotional, reflecting on the days when his on-screen nieces were little girls.
John Stamos Says Life as a Dad Is 'More Beautiful Than I Imagined' (Exclusive)
"I got a little emotional because -- Bob [Saget] has come over and Dave [Coulier] and Lori [Loughlin] -- all of a sudden you see it, like, 'Oh my god. There's Candace and Jodie, and you know Stephanie and DJ and Kimmy Gibbler holding my little baby.' It got to me."
"I did have a flash of them [being] really little," Stamos recalled. "I flashed to Jodi when she was running around here, like, 'How do you roast a turkey?' And I was like, 'Wow.' It was sweet."
ET had previously caught up with Stamos last month, where he also reminisced on his Full House days and how being a TV uncle prepared him for being a father. Watch the video below to hear what he shared.