To run a task immediately after the Server service has started use a batch script to start the service:
net start EasyMorphServer timeout 10 "C:\Program Files\EasyMorph Server\ems-cmd.exe" run http://10.20.30.40:6330 -taskID fdd6a942-b263-4c5d-92e2-22bcaba7a9ce
The batch script must be run under an administrator account.
The timeout is optional but helps make sure that the service is running.
The taskID to run you can get from the URL in the task properties page: