There is a specific importance in writing a Start Up Business plan on dotted line for your start up business. The writing helps like a Bible for the entrepreneurs and acts like roadmap helping to navigate the different stages of business from strategy, planning to investments.
The business plan when in written can help identify potential challenges and devise strategies for future reference, financial projections, details of business growth from inception to setting up the entire operation process.
Here is a video that outlines in details
How To Write a Start-up Business Plan in Entrepreneurship