Closing journal entries are dated as of the last day of the
financial year that you are closing. For example, it you use a
calendar year and are closing the period from January 1, 2012
through December 31, 2012, your closing entries would be as of
"December 31, 2012."
If you had a fiscal year which ran (for example) from October 1,
2011 through September 30, 2012, your "fiscal year 2012" closing
entries would be dated "as of" September 20, 2012, because that is
the last day of the financial year that you are closing, even if
you physicially make the entries after that date.