What is a good time to spay a female?

[gail marshall]

I have a female who is 5 mos old. I don't recall when females come into their first heat. I am also concerned about over anxious vets who wanted to spay her at 6 months.

My last setter, I waited until her 3rd heat before I spayed her, but that was because I bred her for one litter.

I do not intend to breed this little female.

Any advice from all who have had much more experience to offer?