Share 'Sales Forecast help with Business Plan/Marketing Plan'

Hi Everyone I am currently working on my sales forecast on my business plan. I am not sure what would be a reasonable sales forecast for my a start up drink. For example is it reasonable to have a start up total unit sales of 3,000-5,000 the first month with a growth of 50% each month for the 1st year? If we did 3000 units that would be a total of 777,488 units the 1st year at 50% growth each ...