[lisatodd]

i think it is 7 months but more than often, they are still too young to know what to do. most don't stud until 1 1/2 yrs of age. 7 months is still a puppy and all they want to do is play and not get down to business. also, their sperm may not have matured by this age.
each yorkie is different but i do know for the most part, they will usually stud after a year of age.