@dijsil If I am right, you have your golden machine with the OS installed, configured and with sysprepped, after all this, you shutdown the vm. This is the right time to upload the image to the FOG server. You must to create a upload image task for this machine, and if you have it in the fog server configured like a host, the machine will boot WOL, and load the FOG client, for upload the image to the server.
This is the image you must to deploy later to the other machines. You don’t need to make nothing more before upload the image, as long the image is a capture of the OS.