Normally, the time and date will be calibrated automatically after satellite signals are located.
If your device can't show correct time, pls review the article below to fix it :
1. Set your device to the correct time zone.
Go to see article Set Time Zone for My iGS618 / iGS620
2. Locate GPS signal.
Go to see article Locate GPS Signal for My iGS618 / iGS620