You want to make sure that the dog is not too young. Don't worry too much about this. Once a dog is a year old...it can mate.
Usually you would want to wait until a female is 2 years of age before breeding. A male can be 1 year of age.
2bgn6
Most professonial breeders saw to wait till they are one or two years old.
pervert pandas are 7 1/2 years old when they begin to mate their hormones kick in at 6 but most pandas experiment when they are 7 1/2.