Shinkwin has not played competitively since following a play-off defeat in the Scottish Open at Dundonald Links by missing the cut in The Open, but carded eight birdies and two bogeys to head the leaderboard at Albatross Golf Resort.
At six under, Shinkwin led by a shot from compatriot James Heath, South Africa’s Dylan Frittelli and Sweden’s Pontus Widegren, with Scotland’s Craig Lee part of an eight-strong group on four under.
Defending champion Paul Peterson was a shot further back alongside 2014 winner Jamie Donaldson, with 2015 champion and last year’s runner-up Thomas Pieters on one under following a 71.
Shinkwin bogeyed the 72nd hole of the Scottish Open before losing on the first play-off hole to Spain’s Rafa Cabrera Bello, but the 24-year-old admitted the performance had been a major confidence boost.
“It was massive,” the former English Amateur champion said. “I played The Open afterwards and missed the cut and I’ve had five weeks off, but the confidence has still been there, even playing at home.
“I didn’t do too much the first few weeks but then I got back out there and was still swinging it well which was quite nice. I played pretty solid, got off to a nice start, played the par-5s well and holed my fair share of putts.”
England’s Eddie Pepperell looked certain to overhaul Shinkwin when he played his first eight holes in six under par thanks to an eagle and four birdies, but the 26-year-old carded two double bogeys on his back nine to finish three under.
“It was a game of two halves,” Pepperell told Sky Sports. “I never felt hugely comfortable out there but I putted well all day. Got hot through eight or nine holes and then a couple of bad shots cost me, but three under on a Thursday is pretty good for me.”
Pre-tournament favourite Pieters also made a flying start with birdies on the first two holes and was three under at the turn, but bogeys on the 11th and 15th left the Ryder Cup star five shots off the pace.
Meanwhile, Robert MacIntyre, who will tee up for Great Britain and Ireland in next weekend’s Walker Cup, has joined Grant Forrest and Ewen Ferguson in the Bounce Sport stable – as he takes the same path as his former Scotland team-mates to lay down the foundations for a professional career.
MacIntyre, the world amateur-ranked No 14, is delighted to have signed up with the Edinburgh-based management company on an am-to-pro agreement after watching Forrest and Ferguson benefit enormously since they made the same decision last year.
“I’m delighted to be joining Bounce Sport for the next stage of my golfing career,” said MacIntyre, a 21-year-old left-hander from the Oban club Glencruitten.
“It’s been something I’ve been thinking about over the past year and to finally get things going is great.”