We generally recommend allowing 6-18 months to make it through one grade. We realize this is a big span of time, but everyone is different and the time it takes you will depend on your learning style, the quality of your practice, discipline, and other factors, as well as your goals. So be flexible and allow the journey to take as long as it takes. You can certainly push to accomplish certain goals in a fixed amount of time, but plan on allowing more time than you at first estimate.