And with just a little more data you can actually determine how many customers you would need for each year you plan for and how many leads you would need. From that you can actually determine what size market you would need and whether your market is big enough to supply those leads that could be converted into customers.
I mentioned that the 'writing of a business plan' as one of the pivotal steps involved in setting up a successful business. By now you should understand the need for writing a business plan. Writing a business plan, for a traditional brick and mortar business, will probably take a lot of time. It may take up to 100 hours or even more. For obvious reasons, a new business needs to carry out a lot of research before a business plan can even be developed.