Can you open a terminal windows and run the command: ntpq -p
Something like this.
$ ntpq -p
remote refid st t when poll reach delay offset jitter
tok-ntp-ext.asi 188.8.131.52 2 u 1244 64 1 323.229 -433.79 0.001
The above is from OS X 10.9.5 and the offset is in milliseconds.
The offset is often a little worse in OS X than other *nix operating systems, due to the apple ntpd / pacemaker implementation. But it should be good enough for most people and certainly not offset by minutes.
Edit: as mentioned above, some corporate networks block ntp.