"If it's next week I'll grab it with two hands but if it's a bit later down the track I'll be more than happy as well," he said of a possible All Blacks debut. "I'm just willing to learn and soak up the environment and advice. It's exciting times."
Exciting for his family too, of course, although he was surprised to find his father Kevin, a former lock or loose forward who played 167 games for Taranaki, was in bed late on Saturday night when he rang from Sydney with the good news.
"It was unusual for him to be in bed on a Saturday night. Normally he's out drinking with his club rugby mates because he's still running around," Barrett said. "He was rapt. He said he wasn't going back to bed after that."
Barrett played fullback at school and for the New Zealand Under-20 team last year and his ability to play at the back could be the difference between making the reserves bench and being left out of a matchday squad altogether.
He said he was comfortable at fullback but, having made the switch to first-five while playing under Gordon Tietjens for the New Zealand sevens team in 2010, that was where he felt most at home.
"It just felt right. I like having my hands on the ball and being involved and directing the ship."
Julian Savea is the other Hurricanes' new cap in the All Blacks squad and Barrett said the big wing's finishing ability was great for everyone's confidence.
"He's such a threat with ball in hand so it's great to play inside guys like that.
"He can chip, he can run around guys or he can run over them so he's the triple threat. There's no doubt the Irish will have to look out for him."
Savea, also 21, is a big chance to make his debut on the left wing for the first test at Eden Park on Saturday, saying: "Everyone's striving to start ... I feel like I'm ready, that's the reason why the coaches picked us. I'm just looking forward to getting stuck in this week."