Evaluating and Reviewing the Plan: Decide a time_frame for your marketing plan and determine the metrics on which you will measure its success. Measure the results it produces and compare them with the expected success. This will help to know whether any corrections or modifications are required to make the plan more successful.
When I ask entrepreneurs and small business owners, it is not unusual for not having any marketing plan. I once read that Sir Richard Branson never had any marketing plan when he started the 1st Virgin business many years ago. In fact in one study of entrepreneurship (I couldn't recall the name of the study) was that as much as 50% of entrepreneurs and business owners don't have a business plan and marketing plan when they first started the business.