How long it takes depends primarily on whether people want to buy whatever you are selling. If you are selling a product or service with many competitors and have no reason why someone should buy from you, it will be a long slow go and depend on your personal selling skills.
If you are selling hamburgers to a "starving crowd" - or the equivalent, you will sell a lot right away. (think the only food vendor at a baseball game).
This is why I recommend identifying the market first and then the product or service later, once you know what they want.
Joe
