http://netbsd.i2p/docs/guide/en/chap-net-services.html
As you've seen, ntpdate is not difficult to use.
The next step is to start it automatically, in order to always
have the correct system time.
If you have a permanent connection to the Internet, you can start
the program at boot with the following line of /etc/rc.conf : ntpdate=YES ntpdate_hosts=" ntp1.inrim.it " The name of the NTP server to use is...