Need an additional field “Days To Go”

We need an additional field “Days To Go” on appointment or meeting:

Figure: The date is good, an additional field "Days to Go" would be even better. A good example of this field is on the homepage calendar of www.ssw.com.au

Figure: The date is good, an additional field “Days to Go” would be even better. A good example of this field is on the homepage calendar of www.ssw.com.au