Select a cell to enter the kickoff date. Let's make it AA1 for now.

In your tracking cell, enter the following formula:

=TODAY()-$AA$1+1

Now Ctrl+1 to open the Format Box, select Category: Custom and enter this custom format:

0" of 40"

Last step is a macro to reset the date in AA1.
Sub Reset()
    Range("AA1").Value = Date
End Sub
Put that on a button, or just run the macro manually.