The goal of therapy is to get you back to speed and control your pain. It might be unrealistic to expect your pain to go completely away during the course of your treatment. It is hard to predict when back pain will go away. But your therapist can help you find ways to control your pain better.
In most cases, your visits to the therapist will end when you can manage your pain and you are moving much better. Your therapist will develop a home program of exercises and stretches. The home program is an important part of your treatment. Stick with it. Recovering from back problems is a long-term process. Keeping your back strong and improving your fitness level will help you avoid--or at least minimize--future back problems.