yes, I think it can take up to 24 hours for the resource to appear in the inventory. RHQ/JON uses "discovery" mechanism to find out about new stuff on the machine, which is a very expensive process that we try to limit the impact of by running it rather infrequently.
You can force the discovery by running the discovery operation on the platform resource (i.e. the parent of your EAP resource). Make sure to set the "detailed discovery" attribute of that operation to true, otherwise only the top level servers will be searched for. This will take a little while but when the operation is done, you new element should appear as a new resource in the inventory tree in JON.