Timelines vary greatly for creating a plan depending on the writer's experience, the business type, the detail required, and how much industry and market research is necessary. There may also be other factors. In most cases, however, a detailed plan can be created within 2ι weeks.
Now let's say you estimate your conversation rate to be 3% of turning leads into paying customers with the advertising method you're going to use, how many leads would need to contact to get 387 customers? Simply divide 387 by 3% and you get 12꽭 leads you're going to need to contact. Then the question is; is your market going to be big enough to provide you with 12꽭 leads for the next year and how many will you need each of the following years?