Typically yes. And the more traction you already have, the more historical info you have on sales, the farther into the future you should model. 3 years is typical if you have traction and knowledge on which to base your projections.
A year would be a minimum amount of time. We all know that forecasts are guesses so, what's important is how you've determined the numbers. Of course the numbers need to show that the business is worth an investment.
The rational justification of the numbers to demonstrate your expertise in the market is the most important part. You need to tell a compelling story that's supported by the data you present.
