Breeding Jack russells

Question
Could you please tell me what the earlist and safest time for a jackrussell to have a litter of pups .Thanks Neil

Answer
I didn't really want to answer this question because if you don't know the answer to it, you are not prepared to be a breeder. However, I believe there is a lot for people to learn here so I will attempt to describe some important things. There is SO much to learn and know about breeding. It takes an enormous amount of time, education, and it costs a lot of money if you are going to do it right.
You need to make sure you have a healthy pedigreed stud dog, and you have to pay for his services. You need to have the female and the male tested for brucellosis or other sexually transmitted diseases.  Both dogs need to be in tip top shape and up to date on all vaccinations. You'll need to have the stud stay with you for at least 14 days during the breeding cycle. You need to buy or make a good sized, safe, warm, whelping box. You need to be mentally prepared to lose your dog during the birthing process. You need to be educated in emergency veterinary procedures in case she starts hemmoraging (bleeding profusely), you need to know how to get a stuck puppy out of the birth canal, you need to know how to resuscitate a dead puppy, you need to know how to tie off the umbilical cord without injuring the puppy, you need to buy special food for the mother during the growth period of the pups. You need to take mother and pups to the veterinarian for healthy pup check ups. Jack Russell Terrier puppies need to have their tails docked by the veterinarian, some have their dewclaws removed as well, you need to have all the puppies vaccinated at 7 weeks of age, you need to have all the puppies dewormed at least once but usually twice, and most importantly you need to make sure they will all be placed in approved and loving homes with people who understand the Jack Russell breed. People want them when they're puppies because they are so adorable but when they grow up and are not trained properly, they can be a hard breed to live with. Client education is crucial.  It is not a cheap or fun hobby to breed. It is a SERIOUS,  VERY EXPENSIVE, and highly demanding job. PLEASE THINK this out seriously before you breed.