
Have to agree with JG. A bitch is ready for mating ideally just after she has ovulated,a and this varies from bitch to bitch and even season to season in the same bitches.
I have just had a bitch mated and she went to stay with the stud dog on day 12, the male on first meeting was flirtatious she negative, but day 16 they were like Derby and Joan showing no inclination to mate.
Stud owner took her for a premate blood test that showed she was only imminent for ovulation on day 16 and was actually mated days 18 to 20.
I counted from the first day I had colour using the tissue test, so it could be had I just waited to see spotting on floor I woudl have not seen any for another day or two making the mating days 16 to 18.
In my breed I have never had a fertile mating before day 14.