You could create a group policy to run this on startup
To synchronize the domain controller with an external time source
Click Start, and then click Command Prompt.
In the Command Prompt window, type the following line, where peers is a comma-separated list of IP addresses of the appropriate time sources, and press ENTER:
w32tm /config /manualpeerlist: peers /syncfromflags:MANUAL
The time sources you choose depend on your time zone. For example, if your domain controller is located in the Pacific Time zone, this line might read:
w32tm /config /manualpeerlist:131.107.1.10 /syncfromflags:MANUAL
In this example, the IP address of the timeserver is used instead of the fully qualified domain name for security purposes.
Press ENTER. You should get a message that the command completed successfully.
Type w32tm /config /update
Press...