That didn't quite eventuate, though. Havili couldn't crack the first XV - being seen as too small. And so it was off to start a building apprenticeship, working for his granddad, and slugging it out in club rugby.
From there, he eventually made the New Zealand under-20s but only as an injury replacement.
Nothing ever came easy.
"When I missed out on the first XV and stuff like that it taught me quite early that it's not always going to go your way," Havili tells the Herald in London ahead of his fourth outing for the All Blacks against the Barbarians. "It's probably a good reality check at that age that it was going to be a lot of hard work and time. I always had that goal that I wanted to play professional rugby. I stuck to that goal. There was a lot more setbacks than I thought I would have but it helped me get there in the end."
Havili put down the building tools once he secured his first professional contract with Tasman. The 22-year-old has since progressed to become the province's first homegrown All Black. It's an accolade he is proud of, and one he embraces if it means he inspires others the region to follow in his footsteps. But it may not have happened without the help of Leon MacDonald, the Tasman coach and former All Black, and Dagg.
"Izzy was massive for me - he put me under his wing. My first game at fullback for the Crusaders he helped me that whole week and so did Leon with the positional side of things. Izzy said just to back myself and to hear it from a guy that's been there done that is huge for a young player."
Havili has always played fullback and second five-eighth; a strange combination. It is far more common for someone to play all back three positions or both midfield roles. While that versatility speaks to his rounded game - he can kick, pass, run, and slot goals - he appears much more suited to fullback and has finally found a happy home there.
"He looks so much more competent and confident at fullback," All Blacks assistant coach Ian Foster said. "He's got a nice calm, decision-making process about him.
"His form for the Crusaders over the last 24 months and particularly last 12 months meant we were looking at him closely and now he's got a great opportunity.
"He hasn't been overawed; he's been confident and he's kept his head down and really focused on learning and the expectations and getting to know his team-mates because so much of his role is about working with people around him."
What a year it has already been. From establishing his presence in the 15 jersey to winning a Super Rugby title and scoring a try in Argentina on test debut, Havili could barely ask for much more.
And yet there's a sense he's only just getting started. Tomorrow he'll run out at one of rugby's great venues in-front of 70,000 people - his good mate Jackson Harvey among them. But when he returns home for a spot of whitebaiting, hunting and swimming over summer, only then will he appreciate how far he has come.
"It's all gone so fast once I finish this Northern Hemisphere tour and get home I'll have a few beers with family. That's probably when it'll sink in and I'll reflect back on what a great year it's been. There's definitely been times when I've been sitting at home or on the plane just thinking about where I've come from over the last two-to-three years. It's something I'm really looking forward to carrying on. It's been a dream come true.
"Hopefully I can stick around a wee bit longer."
