Do not try to write your business plan in one sitting. As I mentioned in the beginning, for a traditional brick and mortar business, it could take in excess of 100 hours to compile all of the information needed into a comprehensive but yet understandable document. For online businesses, probably not that long. But your final product should be well thought out, well documented and easily understandable.
Far be it from me to dampen your enthusiasm, but you should give yourself every opportunity for success. That's what the planning part of the process of creating your business plan will do. By the time you have pressed your way through it, you will not merely have some neatly arranged document to keep on file, you will have a working tool that addresses the essential factors that influence your future.