I would advice against using other tools like ntpdate or timedatectl since they most likely conflict with NTP.
If you're using the image just as a server using dpkg-reconfigure tzdata should be fine, maybe just do a
service ntp restartto force a resync of the time.
But aside from that you probably have nothing to do.
If you're using a Desktop such as MATE you might have to check on the settings of your desktop since they may overwrite the time you get from system.
Just typing "date" in a terminal should always show you the current time and timezone you operate in, no matter what the desktop shows.
If you don't have an internet connection it can be a little tricky since I don't know if hwclock is storing the time properly.
I know that by default NTP writes the current time and date to hwclock when you reboot or turn off your device, so the last set time will be pushed in the RTC, so if the time on your system is already wrong, turning off the device will store the wrong time as well.
If you use wireless connection and don't have internet when booting up, ntp might be somewhat slow and can take everything between 2mins to 1hr until time is synct. Restarting ntp when you have internet connection can speed this up.