Hope this helps.
C:\Documents and Settings\jmunshi>sqlplus /nolog
SQL*Plus: Release 188.8.131.52.0 Production on Wed Jul 3 17:18:14 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
SQL> set time on
not clear what you exactly want..
you can also try the way
SET SQLPROMPT "_DATE _USER> "