Today's date always as a default in Options

When refreshing a report, I want to have the options window always show the latest date or last date of previous month as default even if I overwrite the date in the options window.

I've come up with the following:

On the Options page under the Lookup column I use =NL("Lookup",c3:d3,"") then in c3 I put =NP("Eval",Today()) and in d3 =DATE(YEAR(c3),MONTH(c3),0) which gives me both today's date and the last date of the previous month.

This lets me overwrite the date in the options window then get today's date or last day of last month's date back. Very convenient for doing month-end reporting.

Has anyone found another or better way?