Thank you for the opportunity to help you with your question!
Essentially, a relatively small business plan has to take approximately 100 to 110 hours to create. However, in most cases business owners usually take nearly 220 hours to create a well presentable business plan.
It is important to note that it defends on the nature of business plan you are writing and how well researched you have done to come up with business plan. Therefore, if you have done a thorough research on your business plan, it will take short time to create it. Again, it defends on the complexity and nature of the business you are intending to start, thus your business plan reflects the nature of your business.
Please let me know if you need any clarification. I'm always happy to answer your questions.