When a female dog goes into heat how long should it be before she is taking to her stud?

A three week wait will give you the prettiest puppies.

since your asking here time to get some books and research pregnancy and whelping before you decided to breed.

depending on your breed you may require a c-section to deliver the puppies or they will not be born, if you have a small breed and breed with a dog even 5 pounds more thanher, your looking at an emergency happening. Even medium & large breeds can have issues. Is trying to get her pregnant worth the risk to her or resulting puppies/ she could get an infection known as pyometra even without pregnancy resulting and could kill her.

if you breed her do you have 9 wks to take off from work to tend to the family of puppies. do you have the time to even take off 2 weeks for the whelping and delivery? because dogs do need help, they are not wolves, and if you think they are then you should read science of dogs. do you have the money to afford 7-8 wks of care, food, vet bills, vaccinations. do you know your states law? do you plan to keep any puppy produced that can't find a home or will you just toss it to the local shelter because it costs too much to raise it?

breeding and raising puppies is NOT cheap.

When she first comes into season, day 1 of bleeding, you need to take her to your vet to have a Vaginal swab taken for a C & S to ensure that she has no infections that can prevent conception, cause problems to the stud dog and/or the unborn puppies. After you get the all clear from the lab you will need to start daily blood tests to pinpoint her exact time of ovulation, you should start this about day 7 or 8. This will give you the optimum time for mating your girl.

for responsible pet owners, never.

they keep their female away from all males until her cycle is over, and then have her spayed.

Never