Please read the ntpd document first:
-g
Normally, ntpd exits with a message to the system log if the offset exceeds the panic threshold, which is 1000 s by default. This option allows the time to be set to any value without restriction; however, this can happen only once. If the threshold is exceeded after that, ntpd will exit with a message to the system log. This option can be used with the -q and -x options. See the tinker command for other options.
1000s = 16m40s. And I don’t know why you need to edit your server time again and again… If you insist on using ntpd (not ntpdate or sntp) to sync time then use the tinker command.
tinker [allan allan | dispersion dispersion | freq freq | huffpuff huffpuff | panic panic | step step | stepout stepout ]
This command alters certain system variables used by the clock discipline algorithm. The default values of these variables have been carefully optimized for a wide range of network speeds and reliability expectations. Very rarely is it necessary to change the default values; but, some folks can’t resist twisting the knobs. Options are as follows:
panic panic
Specifies the panic threshold in seconds with default 1000 s. If set to zero, the panic sanity check is disabled and a clock offset of any value will be accepted.