That is the question. I am glad I don't know anything about this, but for the record I am going to the vet on Thursday for my annual innoculaton and Daddy is going to ask her when is the best time. He has read that it should be when a dog is mature and I am not yet. My trainer and my vet recommend it, and Pawstretchers won't mind me now until I am "done".
While researching this subject, Daddy has found the following articles of interest: