The Englishman was playing in his rookie season on the European Tour in 2016 when he followed an opening 81 at the Open de España with a second round of 89 at Real Club Valderrama.
That 89 is still his highest ever round on Tour but five years later he went 24 shots better to sit just a stroke off the lead heading into the weekend in Sotogrande.
And he revealed he had been taking some pointers from watching Sergio Garcia - a three time winner and former host of this event.
"I shot 81-89 in 2016 and finished dead last in two rounds, not surprisingly," he said.
"I think the more you play the course, you understand it. I've watched Sergio play it and he seems to hit driver everywhere. I hang my hat on being a good driver of the ball so I think that's the approach we've taken - if I can take driver out let's do it, let's back ourselves to hit it straight.
"You don't want too many five and six irons into the greens even with it being a bit softer than usual so that strategy seems to have worked relatively well, certainly today, and hopefully we'll keep that going."
Canter flew up the leaderboard as he turned in 30 and two more birdies on the back nine gave him a share of the lead before he made his only bogey of the day on the 16th.
"The front nine I didn't really miss a shot," he said. "There was a couple of holes we deliberately played away from, trying to hit it to 20, 25 feet, and then a couple where there's a window to get it close.
"I thought the pins were more generous than yesterday but even so, I was obviously delighted to go out in five under which is great round here.
"The perfectionist in me would have liked to play the last three holes better.
"I made a bad swing off 16 and then that maybe slightly took me out of the flow I was in. Up until then it was probably the best 15 holes of golf I've played on Tour.
"I've had lower scores out here but in terms of control of the golf ball and on a difficult course with quite challenging conditions, certainly on the front nine, it was really, really good."