I realize that it varies, but should 2 years (beyond real estate classes) be long enough to become self-sufficient ?
First, what is your criteria for "self-sufficient"? You know that the first level license you get is a salesperson license. You cannot work for yourself but need to work under a broker.
Your success will be a result of your networking ability and the broker's office reputation. If you are in your 20's, have a wide circle of friends, and they are at the point that they are ready to buy their first home, you have a great start. From there, building your own reputation and working to build your listings (for sales) will get you to the 2 year mark, when you can take the broker exam and open your own office.