Unfortunately, there is no easy way to tell how many sessions one will need.  Everyone is different and will respond to treatments in their own way.  Typically, you should start seeing improvement within 1-3 treatments, however what you get out of the treatments will be reflected by what you put in.  Those people who are engaged in their rehabilitation, make the necessary lifestyle changes, and are ready to delve into and face the things they are holding onto and are holding them back will see the biggest results.  Those who take less responsibility will find their progress slower.  Wherever you are on your journey you will be given the necessary tools to help support you where needed.  Ultimately however it is up to you how fast you progress in your health.