I think you'll be more than pleased with your results. So you have an excellent idea for a business. You have the motivation and the adrenaline to give it the big bang. Whether you have decided to seek advice from a professional or not, it is always wise to create one yourself first. This is the soul of the business plan.
Many people interpret it as the advertising and promotional side of the business.
It is merely a route map of how you intend to reach your business objectives. Being able to take the concept, translating it to a plan, and executing it requires ingenuity. That is precisely the reason why you need one. Mistakes can be costly. So the most optimum way is to make the mistakes in your head.