How to plan for career at early age?

While doing the planning for career at early age, one should try to answer following relevant questions:

1. What are my passions & interests? What are the things I like to do tirelessly for hours & hours? What are my long term career goals? What should be my short term goals to move forward in direction of long term career goals?
2. Why should I choose one field as my career out of multiple passions & interests I possess?
3. How can I get the guidance from career experts in the field?
4. Where can I get the help of career counselors in local vicinity?
5. Who is the right person to whom I should listen to for career counseling? Naturally it should be the one who is expert in that field or expert in career counseling who can even guide you with other available options.
6. When should I start planning for my career? Most of the time, people who are top rankers in their field are the ones who started planning for their careers & moving in that direction at very early age of 7 or 8 years.