i have been told the best time to spay your dog is 3 month after their season,
i myself have let one of my females have a season and i got her spayed bang on 3 month after it and i will do that with the others for sure.

to tell the truth i would never get any bitch of mine spayed be4 having a season, i would let them have 1 season at least.

i donno about it stunting their groth but i do know it don't stunt them width ways lol, my female ended up gaining weight and to tell the truth, she looks well better for it, nice and chunky