Some improvement in symptoms is usually seen within the first week or two, but to get healing, a longer time period is necessary. However, at least there are no negative side effects such as stomach irritation or liver damage that can occur with extended NSAID usage. Each pet is individual, so I can't predict what result your shepherd will have, but we have been pleased with feedback that we have had even with older pets.
I would also suggest that you do a few other things if you aren't already doing these. Give digestive enzymes with each meal, probiotics and a high quality fish oil supplement daily. For a Shepherd, I would also give a choline product such as Geri-Form to help improve the nerves. Together with Arthro-IonX it has a synergistic effect for faster healing.
Please let us know how you progress.