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.
Some people think that they do not need a business plan for a small business. But let me make it clear that the size of the business doesn't matter. Whether small or big, you need a plan. If you need a plan as an individual and for your family, then why not have a plan for your small business? Like for individuals and families, you need to plan for your online small business. A business plan shows you what you would like to achieve and how to achieve it. Although not all plans are written down, a good business plan should be written down. If you have it in your head, it's high time you spent some time to write it down for better results.