But do not be too paranoid, make sure you are showing it to people you trust, whose feedback you welcome and can be genuinely useful in guiding how the plan takes shape. Very often when working as individuals we get very close to certain details and miss out a big thing that has slipped your mind. You can concentrate so much on essential financials and supply logistics, but overlook other issues like marketing or opening times. By showing the plan to someone you trust, they can have a look and see what might be missing or worth developing more. Getting that valuable second opinion on how robust your idea is will put you in a much better position to start and keep going successfully.
The "One Pressing Issue" Plan: Business planning does not stop the day you open for business. Under the best of circumstances you should be revisiting your plan once or twice a year to see how things are going, and where perhaps you've veered away from your original goals. Remember, changing the direction of a business isn't always bad, but it should be intentional.