Locke, who won the Barassie Links Classic, the second tournament of the new campaign by three shots with a brace of 65s a month ago, opened with a 66 at the Glasgow venue.
The five-under-par effort earned the former Scottish Amateur champion a share of the lead with Jeff Wright and Steven Maxwell in a bumper field of 82 players.
Locke, who is mentored and managed by the circuit’s founder, Paul Lawrie started birdie-eagle-birdie to be out in 32.
He then moved to seven-under with birdies at 13th, 14th and 15th before taking some of the gloss off his day’s work by dropping shots at the 16th and 18th.
Forres man Wright, who had earlier birdied the first and eighth, 11th, 12th, 14th and 16th, also finished with a bogey.
Maxwell, meanwhile, signed for a bogey-free card, which contained birdies at the second, third, seventh, 16th and 18th.
Cantley, who won the Royal Dornoch Masters in a play-off at the end of last month, sits a shot off the lead along with Ryan Campbell and amateur James Wilson.
As well as making an eagle-2 at the 13th, Cantley carded six birdies while Campbell recovered from an opening bogey to make his strong start.
Another amateur, Gregor Graham, opened with a 68 to sit in a group that includes Darren Howie, the younger brother of Craig, who recorded his maiden win on the Challenge Tour on Sunday.
Euan McIntosh, who is gearing up for his debut on the Legends Tour, also opened with a three-under effort, as did Jack McDonald, James Johnston and Joe Bryce.
Tour commissioner Lawrie opened with a 69, which was matched by amateur Ruben Lindsay after he covered the last four holes in three-under.
LET player Kelsey MacDonald, who also finished strongly, opened with a 71 as she joined 32 others in breaking par, with Gabrielle Macdonald and Clara Young signing for 72 and 73 respectively.