Thank you for all the advice.
I just wanted to add that I do take my vet's advice normally. However, he is the one that told me that Science Diet is great food for my yorkies.
I have learned from being here that it is anything but 'good'. Our vet is a really great person with over 30 years experience. That being said, we live in an extremely small rural town. The vast majority of my vet's clients are of the livestock variety. He has always been good and really helped my Mom through some pretty hairy situations when she was breeding Cocker Spaniels, but I don't think he's really the best source of information on some things dealing with these tiny yorkies. But the nearest other vet is over 30 minutes away and I do have a good history with my vet, so I am sticking with him. I listen to what he tells me, then I come here to double check, just to give me peace of mind.
He and my breeder did however give me the same info that most of you did. Puppy food before delivery (I've just gotten Chicken Soup Puppy and am transitioning Diva to it.), calcuim supplements immediately after birth and during nursing.
Thank you for the knowledgable advice. I'm glad that I can come here and get advice from those of you with years of experience with yorkies.