It depends on the breed... Small breeds tends to mature faster than large breeds..... On average, however, males become fertile after six months of age and reach full sexual maturity by 12 to 15 months.
Can my male eight month old puppy get my eight month female pregnant?
There are two parts to this question- can your puppy get her pregnant, and is she able to conceive?
With regards to your female pup: In order to get pregnant, your dog must be in season. (This is close to the canine equivalent of menstruating). If she is not, she will likely not allow a male dog to mount her, nor will they want to, as she will not be giving off the pheromones to attract him.
Dogs usually have their first season between the ages of 6 months and a year, so if it has not happened yet, chances are it will soon.
However. It is not recommended that you breed a dog in their first season, as have not yet reached physical maturity (this doesn't happen until they are around 2 years old), so for the sake of your dog, and her future puppies, it might be wise to wait a while longer.
Most female dogs can come into season at age 6 months and I am sure male dogs can get a female dog pregnant when they are 6 months old and older - so the answer is most likely yes..