Always aim for about 6 months old, but really it doesn't matter whether it's 2 months or 10 months as long as it gets done.
As for the laser, with my older cat I opted for the laser and didn't know whether or not it really was any better.
Far more important (if it matters a lot to you) is the SKILL of the surgeon. My youngest cat, she was spayed by what is reputed to be the best vet around, and he doesn't believe in lasers. When I got my kitty back, I was AMAZED at the size of the incision... it was literally one inch long. No external stitches, no swelling, nothing. No pain meds, no bed rest (usually I've been told to keep them quiet and from jumping up on things). The vet said "she's good to go" and she was. That changed my mind right then and there that it's the skill and care the surgeon takes, not what tools they use.
I guess that's really what matters with anything, be it artist, carpenter or doctor.
Andrea