I completely agree with Moltar. I think you should get started as soon as possible thinking of business ideas. As was suggested in another board, every day you should right down a couple or a few things you think you might enjoy doing that would benefit others. These can be as simple as starting your own roofing business or as complicated as beginning a biotech firm.
Another question you should ask yourself, would you rather be self employed or an entrepreneur/business owner? There is a BIG DIFFERENCE.
A couple good books to help you differentiate are
Cashflow Quadrant and
The eMyth Revisited