Breed Early To Get Bitches?

When talking to my friend the day of Kaiah's mating she suggested that going early may produce more females, going later more males. This was mentioned to me years ago after Krizzie had her 2 litters totalling 15 boys with one bitch in each litter. I was always under the impression that the male determines the sex of the litter, but I remember discussing it further with Jill Hubbard and she said that it’s the pH level in the bitch’s vagina that makes the optimal environment for survival of either sex and acidic environment will produce bitches while an alkaline environment will produce males. I didn't really consider that I could influence these levels and gave it little further thought.
Tali was mated to Kai, at home with no test. We had a few matings and she had 4 bitches and 2 dogs that survived. When it was time for Asha to have her litter I did an inhouse test at the vets and was shocked to be told on day ten "May have already ovulated - ready for mating." Of course this test was not as accurate as the idexx test and reading back on Asha notes she may well have been mated on the early side - she had 7 bitches and 2 dogs. Looking back with the knowledge I have now Ziva was also mated early as we used Nico, she had 2 dogs and 4 bitches. So maybe it's starting to make sense? Maybe during the early part of when the bitches are fertile that the vaginal environment is more acidic? I don't know .. I'm just pondering through it.
One thing that amuses me is the owners of stud dogs who boast that "he produces large litter." No he doesn't. Mated to a healthy dog with a normal sperm count the bitch always determines the size of the litter. The eggs need to be there to be fertilised ...
Anyway I'm reading this too late to make any different to Kaiah, what will be will be ... but it is certainly valuable information and should you want to read more here is the link.
https://www.akc.org/expert-advice/dog-breeding/breeding-to-predetermine-sex/