A few days later she was chipping out of some sketchy rough Swinging Skirts LPGA Classic in San Francisco, before draining a nerveless six-foot putt on the last to hold off overnight leader Stacy Lewis by one shot.
"Normally they would say sweet 16, but I would say it's sweet 17," said Ko after her win. "I don't think I would have any better birthday week. I won here. I finally turned 17. I [have] been 16 for a long time. Yeah, you know, top 100 most influential people, I don't know what I've done to get there, but it's just a really special week for me."
So, time doesn't actually fly when you're having fun; not when you're a teenager in a hurry to get places.
This is the remarkable Ko's sixth tournament victory, her second since turning pro last year. It is her first on US soil, having previously won the Canadian Open twice.
Ko was not at her metronomic best yesterday, which if anything made her victory all the more meritorious. She had to scrap and claw her way into the lead, following bogeys with birdies, and then showed ticker to stay in front after she found herself in awkward spots on 17 and 18, with Lewis and Jenny Shin keeping the pressure on until the final putt.
"I knew she wasn't going away. Lydia played great," Lewis said. "Every time I hit a shot in there, she answered."
She had to. Going down the 18th, Ko sprayed a fairway wood into the rough. With Lewis and Shin hitting approach shots near the pin, Ko replied with a great shot of her own.
"The 18th hole, I knew how loud the claps were so I knew I had to hit it close and give myself a birdie opportunity," Ko said.
Shin putted first and missed. Ko then found the middle of the cup - rendering Lewis' short birdie putt moot - as the cameras panned to her father Gil Hong Ko, who rarely attends his daughter's tournaments.
"I am not going to cry now," Ko said. "All of the tears are gone. But it is very special to have him here. Tears nearly ran down my face after I made the putt and during the [victory] speech. Having your parents here... you may lose friends but you are not going to lose your parents. They are always with you. That's what made me feel a little emotional. I tried to make myself not cry with happiness but it was coming to that point."
Ko will move up two spots to No2 in the next world rankings, leapfrogging Lewis and Suzann Pettersen in the process. It will be the highest position held by a New Zealand golfer.
She'll also bank $314,676.
It's an adult world Ko now occupies, but the kid in her refuses to hide. Asked what she planned to do in San Francisco following her win, she innocently replied that the mayor had suggested she go into town and take a ride on the cable car. It might not be what many ordinary people would do with $300k in their pocket, but Ko is no ordinary person.
Ko's tournament wins
• January 2012: NSW Open (a)
• August 2012: CN Canadian Women's Open (a)
• February 2013: NZ Women's Open (a)
• August 2013: CN Canadian Women's Open (a)
• December 2013: Swinging Skirts World Ladies Masters (pro)
• April 2014: Swinging Skirts LPGA Classic (pro).