You also may wanna consider ntp. It's a way to keep the machine in sync with time servers.
If you go that route, download the app, install and just add this to your cron:
05 00 * /path/to/ntpdate time-a.nist.gov && hwclock --systohc
time-a.nist.gov can be replaced with any time server. Each morning at 5 mins after midnight, it will set the time based on the time server's response.
The hwclock part will write it to the hardware, so that a reboot won't screw up the date.
HTH