Nitties, Peter Hedblom, Jin Jeong and Clint Rice all turned in 4-under-par 68s in the first round and are one stroke ahead of a group of eight players at 3-under with eight others two strokes off the leaders' pace.
Tournament defending champion Bo Van Pelt is among those at 2-under 70.
All the leaders opened play Thursday at the 10th hole of the Lake Karrinyup Country Club course.
Nitties three times had consecutive birdies, including on his final two holes. He also had back-to-back bogeys at Nos. 4 and 5, however, among his three bogeys on the day.
Rice had the only bogey-free round in the lead group, getting to 4-under with a birdie at the 612-yard, par-5 seventh.
Hedblom had three birdies and a bogey on each side Thursday, grabbing his share of the lead with a 2 at the par-3 eighth.
Jeong opened with birdies at 10 and 11 and had two birdies and two bogeys in the stretch from 14 to 17. He holed out for eagle at the 444-yard, par-4 18th to make the turn at 4-under. He dropped back with a fourth-hole bogey but regained a share of first with a birdie at No. 9.