I'm not sure you need to establish a corporation until you start earning some real $$. You can have a sole prop or general partnership in the meantime. Remember there are fees and responsibilities associated with becoming a corporation.
There are tax advantages associated with an LLC such as pass through income, etc. But they don't really come into play until you are making some money. Other factors I would consider -- do you have partners? Will they be active in the running of the company?
I would get advice from a good accountant on the pros and cons of forming an LLC now or later.