If you’re using the ‘open level’ node, you can’t do anything while that node is running, because it eclipses everything else. You’ll know when it’s finished, because you drop into the level.
With streaming ( yes that ), you can bind an event to tell you when it’s loaded
and default streaming only calls the complete node after the level has loaded
although you might not agree that its really finished ( the engine definition of ‘loaded’ is quite bare bones ).