The rookie pro was rewarded for not letting those mistakes at the second and fifth holes linger as she carded a two-under-par 69 on the North Course at La Manga.
Helped by birdies at the first, eighth, 14th and 17th holes, the effort moved MacGarvie into a tie for 16th on level-par, just six shots behind leader Maghan MacLaren from England.
“It was good,” said Royal Troon player MacGarvie of her day’s work. “I got off to a good start with a birdie on the first and then missed a couple of putts in the next few holes.
“I tried my best not to get my head down because it was a couple of silly silly three-putts.
“Didn’t get my head down and plodded on and then after that, I managed to get in a rhythm and managed to get holing the putts again and took my birdie chances on the back nine.”
MacGarvie, who won the St Rule Trophy at St Andrews last year, is closing in on a seat at the LET table next year in her first crack at the Q-School.
“I was pretty nervous at the start coming into it, but then I thought, you know what it is just another competition and another round of golf,” she said.
“Just take it day by day and that’s all you can do; you can’t make it out to be this big thing otherwise you will start stressing out.
“I took it day by day and treated it as a normal golf competition and hopefully it will work for me.
“Hopefully more of the same tomorrow. Try to make pars and take birdie chances when they come up.”
Hannah McCook, who finished with a triple-bogey 7, and Laura Beveridge are the next best among the Scottish hopefuls, sitting alongside each other in tie for 41st on four-over after 73s.
A brilliant 67 moved Rachael Taylor into the top 65 on seven-over, one ahead of Heather MacRae, who had made progress after going out in three-under before limping home in 42.