The 19-year-old New Zealander headlines the Australian Open in Adelaide this week, where she will hope to grab her first tournament win in seven months following a barren second half of 2016, her first mini-slump of a stellar career.
Kirk birdied her second hole on Friday afternoon to move to nine-under, a shot ahead of American Lizette Salas and Thailand's Phatlum Pornanong, who have completed their morning rounds.
She has made some sweeping changes in her game to the start the new year.
But all of that didn't seem to matter Thursday, as Kirk birdied her first three holes and four of her first five on the way to a bogey-free 65 at the Royal Adelaide Golf Club.
"A lot of birdie opportunities, and I was just fortunate I got off to a good start and kept the momentum going". A bogey on ninth meant she was again over par, but was back to par with a birdie on 12th and another birdie on 15th saw her get back to red numbers.
Chasing Kirk are a batch at six-under - Taiwan's Min Lee, Korean Chella Choi and American duo Marissa Steen and Jane Park.
"I try and not think of it as "hey, everyone is trying to chase me", Ko, who won the 2015 tournament and was runner-up previous year, added.
"I think that I'm hitting the ball good enough where I can have a lower (round) and hopefully that's the one coming on the weekend", Ko said.
Canada's Brooke Henderson was four strokes behind after carding 69. I have just got to work a little harder.
World No 1 Lydia Ko barely made the cut with rounds of 71-75 and world no. 2 Ariya Jutanugarn (72-72) is tied 39, alongside Aditi.
"I hit my drives good, which is really important around a course like this, but just the putts did not drop", she said.
"It would be a dream come true and something I think every young Australian thinks about at some point", Smith said.
World No.1 Lydia Ko posted an opening-round two-under but Australian veteran Karrie Webb struggled to three-over.