Ideally, you want to set your system time to Zulu Time and then set your timezone variable so that your local software handles everything right for your locale. I would try hard for that solution. But in
this thread we saw that peter.herlihy had a problem with an unusual timezone too. Most modern variants of unix now have very programmable timezone software. But some older versions only really support US timezones well.
It may be that if you use ntp to sync your clocks that you are left with no way to display the correct local time. If so, you may be forced to misalign your system clock. This is unfortunate, but it's what I would do if I were forced into it. If this is the case, you do do not want ntp.
When one of my system clocks is very far off for some odd reason, I do not patiently wait for ntp to correct the situation. I want instant gratification.
So to answer your original question, kill cron, then change the time, then restart cron. If cron sees the time change, it will catch up or stop running until it thinks it resyncs. Also be sure that no one is using "make". It's best to do this at a time when no one is using the system. If that's not possible, let the users know.
Rolling back time
xntpd