Sam Farlow opened with a 2-under-par 70 and is alone in second place, while Robert Mielcarz is the final player in red figures at minus-1.
David Boesel, Mike Bell, Paul Schlachter, Gary Vanier, Michael Walters, David Rasley and Doug Crawford share fourth place at even-par 72 at Victoria National Golf Club.
Simson has won three amateur titles in the last two months, including the British Senior Amateur. He notched five birdies and a bogey in his opening round.
'I've had a real solid summer,' said an understated Simson. 'My stroke average is as low as I've ever been and it's all because I'm hitting the ball much better. I seem to have a good pattern going.'
Allan Small, Bob Clark, Martin West, Greg Reynolds, Bill Leonard and Terry Tessary are tied for 11th place at 1-over-par 73. There are six more players one shot further back at plus-two.
Defending champion Mike Rice posted a 7-over-par 79 in the first round and is currently tied for 68th place.
After the second round of stroke play on Sunday, the field will be cut to the top 64 players for the match-play portion of the event. Each of the match-play rounds is scheduled for 18 holes.