Before the watch has been paired with your smartphone, it usually doesn't show the correct time and date. Once paired, the watch updates the date and time automatically, in accordance to its geolocation, as soon as it connects to the mobile network. You can choose between the 12 and 24-hour time format in the Settings of the watch > Clock format.
If you keep seeing the wrong date or time on the watch, check if the SIM-card has active mobile data and if the watch receives good coverage. Rebooting the device will help the watch to reconnect to the network and update the date and time.
If your watch still doesn't show the correct date and time, go to the Settings of the watch and scroll down until you see the option "Set date and time". Make sure that you have enabled the option "Automatic settings" - the watch will automatically synchronise with your geolocation and update the date and hour.
If you prefer to set your current time zone and date manually, disable the "Automatic settings" to introduce changes.