Yeah I did this:
The Windows installer will set up a Service Wrapper, but leave it turned off by default. To activate it, go to Control Panel / Administrative Tools / Services, select the OpenVPN service, right-click on properties, and set the Startup Type to Automatic. This will configure the service for automatic start on the next reboot.
but still - does not work as I want it to (does not launch at all at start, at least clients can not connect - even that I have service running). Only when I manually run OpenVPN GUI clients can successfully connect.