I have absolutely no experience in this field, so I probably shouldn't comment, but I think you are right on target in how you are working with your dog. Although not every puppy would be suitable for on the job training, obviously yours is and it will work to her advantage. You are in a unique situation. In training guide dogs for the blind, I know they start them out as young pups exposing and acquainting them to the very situations they will have to work in later. I don't see how your situation is any different. The organization you talked to probably has their reasons for the guidelines they have set forth. As long as you have the opportunity to train your dog on the job and the nursing home has allowed you to proceed in this manner, why worry about it. Just make sure your dog gets plenty of play time at home, so she can "be a puppy" as well.