After you enable the WebLogic Management plugin on an instance, the instance registers with the service. The Console, however, does not display WebLogic domains on the instance until after the initial discovery scan, which is scheduled at the top of the following hour. Or, you can start an on-demand scan after the WebLogic Management plugin is running on the instance.
When the scan detects the presence of WebLogic domains, the plugin reports the discovery details to the service. This initial discovery phase can take some time to complete.