I have an 11 month old GSD that hasn’t been socialized much. He is too old for the puppy video you have and was wondering is it too late to train him for good socialization skills?

I have an 11 month old GSD that hasn?t been socialized much. He is a rescue; I got him at about 4 months old and have had him out in public, but he needs obedience training. He is non-reactive to other dogs, cats, children etc. I want to try and train him to be a service dog (I suffer from PTSD) as he appears to have a very good temperament. I purchased the Michael Ellis self study Training with Food. He is too old for the puppy video you have and was wondering is it too late to train him for good socialization skills? Could you recommend a good video to begin with if the one I chose is not the best starting place? I realize only a small percentage of dogs are suited to service work but after training if he isn?t suitable I still want a well trained and obedient dog.