Amour Yorkies I think it is great that you want to be a responsible breeder. Personally I wouldn't buy a puppy from you YET. Seeing the offspring's temperments and being able to speak to references who bought puppies in the past is important to me. I also prefer to buy from a breeder that actively shows their dogs and is a member of the local breeder's association is important. I know that they are very knowledgable about what to look for in the breed standard.
That being said I don't think your age is the issue, if you plan on doing the proper testing and have a mentor that is going to be actively involved with your breeding program, in a few years I think that I would consider looking at your pups
Good luck!