Place this snippet in your /etc/rc.local file so an RPI will sync time on boot

sync_rpi_time.sh

#!/bin/sh

#force time set with NTP server
clear
echo Setting the time and date.  Your sudo password may be required below...
echo
sudo ntpdate -bu pool.ntp.org
echo
echo The time and date are now set to `date`
echo
exit 0