Setting a system clock varies from environment to environment.
In a UNIX-based environment, you can set the clock using the "date" command. Most Linux distros, Mac & Windows should all have options to sync your clock with a NTP server.
You should be within about 5 minutes of our servers. You can determine the delta between your machine and ours by examining the Date HTTP header we send in response to every request. By converting that to UTC epoch time in seconds and comparing to your current UTC epoch time in seconds, you can determine how many seconds behind your clock is from ours.