You can check your current timezone by just running...
$ date
$ Thu Nov 14 00:39:05 CST 2013
You can also check the timezone file...
$ more /etc/timezone
$ US/Central
To set the timezone just run the following command and then follow the on screen instructions.
$ sudo dpkg-reconfigure tzdata
Make sure you also restart cron to pick up the updated timezone.
$ sudo service cron stop
$ sudo service cron start