I'm a great fan of tracking business enquiries which come through from my web site. This keeps me sane when worry sets in after the latest negative comment about the economy, from media, politicians or unwittingly by the Chamber of commerce .
Indeed it's surprising how much business patterns repeat themselves at different times of the year. So much so that I can confidently project the turnover of my company.
If you wish to do this , start with leads per working day (around 20 working days in a month). Split them into groups of different types of customers. Then work out each groups's closing ratio from sales made. You will find your true closing ratio about 2 months back depending on your customer's decision making cycles.
Work out your average sale for each group. Compare your leads to date figure with equivalent figures from last year to get a good indication of growth.
Apply your growth figure as a percentage to last years figures to project your turnover.
Hope this helps.