Hi @peter-g,
Check the property "Enable Smart Tags" by navigating to your desired folder -> Folder properties.
This should add the tags whenever asset is added/moved to the respective folder.
If you are explicitly looking for enabling only when it is first available to the folder and not upon modifying the asset, then try to create Workflow Launchers with Node created event on the desired folder path(No explicit event for move) and select the workflow to be DAM Smart Tags Assets