Hello and thanks for researching this very important subject!
Female dogs that are under the influence of estrogen ("in heat") exhibit a varying amount of vulvar swelling and discharge. Some females show little or no outward signs. The length of time that a dog bleeds varies...their bleeding is just an overflow from the filling uterus, so it may not be a reliable indication of fertility in all cases.
The canine reproductive cycle is completely different from that of humans.
The day that a female lets mating begin ("Day of First Acceptance") also varies, but is usually around day 9 after her first heat signs appeared.
When the female is ready, she is ovulating...she is not ready for mating until the eggs are released from her ovaries. There is nothing to be done until her hormones change and drive her to mate.
***She will play, tease and avoid (sometimes by snapping) until her body is exactly right for conception. Then she will plant her feet in front of the male, flag or press her tail to the side, and allow mating. They may "tie" for about a half hour. ***
Males and females that are not properly socialized as puppies will exhibit problems executing proper mating behaviors. Some females have health problems that will prevent them from completing a cycle to ovulation, or otherwise interfere with reproduction.
Most breeders let their pairs mate once daily every-other-day for three matings after true breeding behavior is seen. This is usually sufficient to expose her eggs to sperm.
Some first-time mothers are very good at instinctively caring for their young...some are NOT!
You should continue researching so that you are completely prepared for any eventuality...be sure to have a good relationship with a veterinary office where the doctor(s) and staff are familiar with breeding issues. You never know when you will need this type of assistance, and often in the middle of the night!
Here is a link to a very affordable and veterinary-school-quality book about canine reproduction and puppy care. This is something you can use to prepare yourself and have on hand when the time comes:
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