Don't spay at all! Waiting for a year will assure proper growth, but beyond that, it removes vital hormones used in a metabolism above and beyond the mere fertility issue. By removing her ovaries, you're basically creating a 75 year old postmenopausal woman.
There is clear and mounting evidence of detrimental health effects especially with Vizslas...google it. Sorry, your vet and "trainer" are just plain wrong, find new ones. The excited urination will not be effected by this procedure, they typically outgrow this.
Gonads (in both genders) are involved in much more than fertility. If you are concerned about the heat issue, then find a vet who will leave the ovaries intact and in place. And as a general statement to others, if this is unacceptable to you, then reconsider getting a female.