A way to point a progress bar to a specific time?

[Miraclezz]

Hello all,

So I wondered if it is able to point a progressbar to a specific amount of time.
For example:

Start date: 10-01-2012
Current date: 15-01-2012
Finish date: 20-01-2012

So the progress bar's current value is 50% because we're half way of days.
I think this is the best explanation I can give.

Thanks