In the announce folder,
right-click on the old copy of announcements.pdf, and select to Rename the file after the Monday date it describes. Follow the naming convention suggested by this example,
041108-nov-08-2004.pdf
where,
04 refers
to the last two digits of the year,
11 refers
to the two-digit month,
08 refers
to the two-digit day; and
All characters are lower-case.