The workshop consists of 10 lessons that can be completed in a week or in a year. The length of time to get quality results depends on how much time you have to devote to completing the exercises and how self-aware you already are. If you're not sure, typically 1-3 months is a good rule of thumb.
As for the time it takes to find your calling, this will depend on how much action you take and how far you are from your dream career. This course is designed to start you off in the "right" direction. You will decide what's "right" by looking at your values, natural interests and aptitudes and other preferences.