You Don't even have to wait for their first season anymore. As long as they are six months of age or over then they can be spayed. It's actually better if they don't have a season first something to do with less chance of developing cancer.
If your not going to breed from her then I think the best thing is to have her spayed. I have booked my two in for next week. They are being spayed using keyhole surgery. Better for them as the recovery time is less and no stitches to contend with. More expensive, but worth it.