Forecasting, like predicting the weather, is imperfect. It is a matter of using the best information available to make the best possible decisions. The business owner should be aware of these limitations, but also understands that it is still better to plan, forecast, and predict than to leave everything to chance.
There are several generally accepted methods of sales forecasting, some more quantified than others. In a new business, forecasting is more difficult, as there is no historical data with which to start.
My business repossession company , develop a sales forecast for the first two years. Assuming that sales will increase, explain your assumptions and how your marketing plan will influence sales over time.