It took about 2 weeks on our dog, he is almost 12.
He takes the oil, pet shop had it, but, now we go to the Piute Indian Reservation, they set up a Mary Jane shop right next to the cigarette shop.
About a third cheaper than pet store.
Hope it works for you.
I buy mine at the pet store for myself. The owner is the one who told me about it as he takes it for pain in his back and shoulder. same as I have...