Harris, who defeated Anders Hultman in a playoff to win the Bay Mills Open Players Championship just three weeks ago, has a one-stroke advantage over Brad Fritsch.
Ken Duke is four strokes off the pace at minus-5, while Scott Ford, Michael Walton and David Mathis share fourth place one shot further back.
Darkness forced the suspension of play until 7:20 a.m. ET on Friday morning, when 14 players will finish their first rounds.
Harris' 63 set a course record at the 7,169-yard Thundering Waters Golf Club, which is PGA golfer John Daly's first 'signature' course.
The course is not yet open to the public, but Harris is already showing that low scores are possible. Or maybe it's just that he's playing that well.
'It turns out if you can hit it well and putt well, you can put up some good numbers,' Harris joked. 'There are times in your life this game is hard, there are times it is easy. Right now it seems easy.'
Harris, the Canadian Tour's money leader, has been busy during the past two months. In addition to his win at Bay Mills, he has four mini tour wins, a runner-up finish at the Montreal Open and a 21st place showing at the Canadian Open.
He struck the flagstick with his first approach shot of the day at No. 1, and saved par after the ball rolled into a bunker. It could have been a bad omen, but not for Harris, who chipped in twice on the front nine and made a relatively easy 3-foot birdie putt on 17 to reach his 9-under score.
'Sometimes when things like that happen, you just think 'It isn't going to be my day,'' Harris said of the first hole. 'I guess it didn't turn out that way.'
Dirk Ayers and Stephen Woodard share 10th place at minus-2 after opening rounds of 70. Six players are tied one stroke further back.