The two-time Scottish Amateur champion fired seven birdies in a six-under-par 65 to share the lead at Lumine Golf, one of four venues.
It was the start Law was looking for after he narrowly missed out on finishing in the top 70 on the Challenge Tour’s Road to Oman last weekend.
Ross Kellett also opened positively at the same venue with a 66 as he bounced back straight away from the bitter disappointment of being disqualified in the final regular Challenge Tour event of the season for signing for a wrong score.
Daniel Young (72), Jamie Savage (73) and Sam Kiloh (73) all have ground to make up on their compatriots at Lumine Golf.
Other Scots to make encouraging starts in the middle of three Qualifying School phases were Wallace Booth, Grant Forrest and Chris Doak.
Booth, a member of Scotland’s Eisenhower Trophy-winning team in 2008, opened with a five-under-par 67 at El Saler to sit in the top 10.
Amateur Liam Johnston also broke par there with a 70 while Chris Robb had a 73, Ewen Ferguson 74 and, disappointingly for him, Jack McDonald 78.
Forrest, who made the cut in last month’s Dunhill Links on his professional debut, bagged eight birdies as he signed for a four-under 67 at Las Colinas.
That left him sitting joint-eighth while Paul Ferrier (68), Bradley Neil (69) and Peter Whiteford (70) also opened with sub-par efforts there. Danny Kay and Scott Drummond signed for 72 and 75 respectively.
Doak’s four-under 68 put him in a share of 13th spot at Panoramica, where Andrew McArthur (71), Paul Shields (72) and Tom Higson (76) are the other Scots in that field.