Try handling the "Syncrhonize" "After" event (and "Failure" for completeness).
For more information:
- https://docs.kentico.com/display/K8/Reference+-+Global+system+events#Reference-Globalsystemevents-StagingEvents
- https://docs.kentico.com/display/K8/Automatic+content+synchronization
- https://docs.kentico.com/display/K8/Handling+global+events