I feel so bad

I have re-scheduled Daisy's surgery to be spayed. I have been reading on line that its best to wait until she has gone into heat at least 2 times before being spayed. Being the responsible pet parents that we are we called the vet to verify if this was true. They told me that it did not matter either way and they usually suggest having the dog spayed at 4-6 months. I explained my case that she was an indoor dog she was only JUST 6 months old and there was no rush to have her fixed. (the research I did also recommended she have at least 1 litter before she is fixed WHICH WILL NOT HAPPEN)
Also due to the expense (over $150) we are going to wait and shop around for cheaper surgery places. If you can wait 2 months there are places that do it for $40-60 which is quite the savings. Also because of what she's already been through being homeless and all and has finally put on weight we are waiting. She will still go in tomorrow for some more shots and a check up with blood work to make sure all is well but the spay will wait so you will have to wait for the cone head pictures at a later date....lol