Darling, who is hoping to play in the Junior Solheim Cup at Gleneagles later in the year, came flying out of the blocks in her event with a four-under-par 67 on the Eden Course.
The effort, which contained six birdies in her opening nine holes, secured a one-shot lead over Germany’s Olivia Bergner as only six players broke par.
“I stuck to my processes well today,” Darling told Scottish Golf. “I had a few bogeys out there but I didn’t let that get me down.
“Everyone is going to have bad holes because it is that sort of golf course, but I stayed patient and let the birdies come to me and I was pretty chuffed overall.”
Darling, who won the inaugural Girls Under-16 Open at Fulford just under a year ago, added : “It’s a marathon and not a sprint so I am just taking each day as it comes.
“I will re-assess tomorrow when I wake up, but I am just happy with what has happened.”
Blairgowrie’s Katy Alexander joined her compatriot in getting off to a promising start with a one-under 70 to sit in a share of third spot.
Over on the Ayrshire coast, St Andrews New member Saleem posted the same score as Darling to earn his lead.
He also leads by a shot and his closest challengers also include a German in Luc Bruer, the highest ranked player in the field.
Bruer’s 68 was matched by Blairgowrie’s Gregor Graham with another Scot, Cameron Adam of Royal Burgess, in a group on 69.
Liberton’s Kieran Cantley led the way as Scotland got off to a good start in the European Nations Championship in Spain.
Cantley’s one-under-par 71 at Sotogrande was the best round of the day, giving him a one-shot lead over Irishman Mark Power in the invidual standings.
The effort also helped Scotland end the opening day in second spot in the team event, a shot behind Ireland.
Euan McIntosh (75) and Euan Walker (76) provided the other counting scores as Jim Johnston, the other member of the team, had to settle for a 78.
In the women’s event, Aboyne’s Shannon McWilliam was the best of Scots with a six-over 78.
Coupled with a 79 from Kilmacolm’s Eilidh Briggs, that left the Scots lying seventh, seven shots behind leaders the Netherlands, in the team event.
Sam Locke, last year’s Open Championship Silver Medal winner, won the weather-delayed PGA EuroPro Tour Qualifying School stage one event at Macdonald Cardrona.
Locke, who turned professional straight after his eye-catching performance at Carnoustie, fired a six-under 66 at the Pebbles venue to head 20 qualifiers.
Southerness amateur Scott Gibson finished two shots behind in second, with Dunbar’s Neil Fenwick and Englishman Kenneth Ferrie both a further stroke back.
Others to progress to the final at Frilford Heath included former Scottish Amateur champion John Gallagher and two others still in the amateur ranks, Callum Fyfe and Christopher Lamb.