I am against early spaying. I believe you should wait until the first heat or the first batch of puppies. The male dog's testicles should be "dropped" before their nuetering.
There is another post on here discussing this exact point of the appropriate spaying/nuetering. There are 2 sides of that camp. I will agree there are benefits of earlier spaying/nuetering but my experience has NOT been positive with that course.
Dogs and Cats I believe need the time for their horomones to kick in. Since they age faster than humans, their teenage years happen around their first heat or drop in testicles. This time helps the animal develop appropriate levels of maturity.
Imagine if you never got to experience being a "teenager". Would your behavior be mature as it is today? I feel it is important that an animal experience the same bodily changes faced in the teenage sexually maturing stage. This allows the animal to develop it's maturity to it's age appropriate.
My cat got early spaying as recommended by the vet. The results have been NOT favorable. She developed "sagging breast" that have NEVER gone away. People assume she is "fat" but it is her extremely sagging skin that makes her appear that way. The skin is NOT tight at all to be "fat". Her maturity level is NOT kitten like but she not into snuggling or being a lap cat at all. My dogs got nuetered at a later age. They both did VERY well. It even helped the one dog greatly after getting nuetered at around a year. (He was adopted from the pound). Shaggy's sexual agressiveness dropped off 90%.
In my opinion, the early spay and nuetering trend is a reflection of animal activist who want to limit the number of unwanted animals in the world. I agree with 100%. That is because many owner's do NOT get their animals fixed at the appropriate time or at all. By convincing owner's to have the procedure done early while their adoptees are being treated for other things is more of a convenience. This assures the owner who may neglect their animal in the long run, that the animal doesn't reproduce making the situation worse. There are also some limited health benefits but that's not guaranteed the animal wouldn't have developed the diseases naturally anyways.
So I happily say it is a good time to spay your pet. I am glad you are doing it. You just may need to hold off until her cycle is over with. Lock her up tight!!!