On a day when just six players broke par on the Ayrshire coast, the 17-year-old Curtis Cup squad member carded an eagle and five birdies, including two at the start of her round, as she signed for a five-under-par 68.
The polished performance from Darling, who won the recent St Rule Trophy in St Andrews, was three shots better than the next best effort as Carlyon Bay’s Emily Toy opened the 36-hole stroke-play phase with an eagle and four birdies.
Three other English players - Lottie Woad, Amy Taylor and Ellie Gower - posted 72s, as did Iceland’s Hulda Gestsdóttir, but the day belonged to Darling, winner of the inaugural R&A Girls’ Under-16 Open three years ago.
“I was just really steady out there today, hit the shots when I needed to,” said the young Scot. “Some of the holes are there like 11, I holed a good putt for eagle.
“I don’t know the rest of the scores and I don’t particularly want to. I just go and play my own game. But it’s a nice start to the week.”
Aboyne’s Shannon McWilliam was next best among the Scottish contingent with a 73, one better than Louise Duncan (West Kilbride) and Hazel MacGarvie (Royal Troon).
Chloe Goadby, Darling’s conqueror at Gullane en route to being crowned as Scottish champion on Sunday, was seven-over after six holes before three birdies around the turn helped the St Regulus player salvage a 78.