I have a table in which I want to have the day of the month automatically
update whenever I open the spreadsheet.

Each month has its own row, and as the month ends, the days gone column
should stay @ the maximum number of days for that month, and the next row
start to be filled in (table below)

Any idea on how I can use the today() function and maybe the if() function,
or WHATEVER to figure this out?

Countdown
% # Days Days Gone
Jul 100% 30 30
Aug 100% 31 31
Sep 100% 30 30
Oct 100% 31 31
Nov 93% 30 28
Dec 0% 31
Jan 0% 30
Feb 0% 31
Mar 0% 30
Apr 0% 30
May 0% 31
Jun 0% 30