Guide Dogs spay their bitches before their first seasons, and I had a Collie cross who was done at six months before her first. It doesn't harm them, but I think you have probably left it a bit late to have her done before her first, as she may come in season any time now. Spaying bitches can prevent a lot of problems such as unwanted pregnancies, phantom pregnancies, mammary tumours and pyometra, which can be life threatening if untreated.
I'd get her done about three months after her season, when her body has had a chance to recover.