There's an article in Entrepreneur magazine online with the title "The Benefits of Bringing In an Advisory Board" and you can read it here. Although it is a rather skimpy article, and doesn't go into much detail about all the benefits, the point can not be made too many times: if you are serious about your business, then start Now to build a Board of Advisors.
I know from personal experience that it makes all the difference in the world to run your business in a professional manner. Unfortunately, most business founders allow themselves to be so distracted by day-to-day issues that they don't give adequate attention to building the structural foundations of the business.
The Board of Advisors is THE best foundation for a serious (non-lifestyle) business. Begin it Now!