Preparation is Most of the Work
The preparation, research, and planning which leads up to the actual writing of the plan constitutes most of the time required to create a business plan. Planning and strategizing cannot simply be done in a day or even a few days. Not only is it important to get feedback from advisors or other trusted parties, which can take time, but the entrepreneur himself must let the plan ruminate a bit in order to uncover aspects he may have missed or thought about incorrectly previously.
Research for the business plan may be the most time intensive element of this preparation. Research should, ideally, be more than secondary sources such as articles, blogs, and industry reports. Primary sources, including interviews, surveys, or focus groups with customers, vendors, and competitors, are very important and more persuasive. Developing data from these types of sources takes a good deal of time. Even information in secondary sources must be pored through carefully to find the nuggets of interest for the business plan. Finally, research into the costs of the business can require calls and even negotiations with vendors to learn about rates and volume discounts. There is no easy shortcut for this type of direct research, which can make launching a much easier process if this legwork has been carefully documented.
Finally, the writing cannot be rushed, as convincing prose does not generally flow under intense time pressure. Time must be given to allow for the writing and then revision of the plan itself. Finally, time should be allowed for proofreading by qualified individuals other than the entrepreneur. This is the only sure way to spot mistakes in the plan at this late stage.