By default when it is powered and connected to your smartphone, your NVX 200's screen will display the time. The displayed time is the one from your smartphone.
However, when it is brand new or in some rare scenarios it is possible that time is not correctly displayed. To set time, you will need to simulate a missed call (or wait until you really miss a call).
Take any phone and call the number of the phone connected to your NVX 200, don't answer the call and let it be missed.
Time is now displayed.
Here is the detailed how-to video: