Dogs go into heat at any time between 6-12 months usually.
They are not normally bred until their third heat to make sure they are mature in body and mind before having to raise pups of their own. Usually they come in heat every 6 months after the first heat.
Dogs are usually in heat for about 3 weeks.
The first week they have a red discharge, then the second a clear or straw colored discharge, then almost no discharge the last week.
They usually are willing to breed sometime in the middle of their heat cycle usually in the range of days 9-14 of their heat season.
Dogs are individuals so you have to see when the female is agreeable as there is no one specific day for sure.
One sign of her being ready would be for her to 'flag' or roll her tail to one side when touched on her hind quarters.
AKC will not register pups to females less than 8 months old at the time of breeding.
Responsible breeders usually wait to breed until all the health testing has been completed to ensure that the pups will not be inheriting hereditary problems from the parents.
This site goes over health issues in this breed in case you want to check them out
Hope this helps you!