As mentioned previously, system time is very important on all devices on a network. Setting the clock using the ASDM can be done by navigating to Configuration | Device Setup | System Time | Clock. You'll be able to select the appropriate time zone, date, and time on the ASA:
The system clock on Cisco devices are in the 24-hour format.
Configuring the ASA to be a NTP client can be done by going to Configuration | Device Setup | System Time | NTP and clicking on Add. This feature will allow the ASA to obtain its time from an NTP server, whether the NTP server is on the inside, outside, or any other interface:
Once you click OK, the NTP server configurations will be presented on the ASDM.
However, ensure you click on Apply to push the configurations to the ASA and save the settings.