how to get callback of datasmith runtime?

I'm using unreal blueprint of datasmith to load revit model in runtime. but i don't know out how to emit callback when the model has been load and rendered.
the "Datasmith Destination Actor" has a property of progress, i try to watch that property but no luck. First, the end value is not 1 but 1.396324 , Secondly, event when progress reached 1.396324 the hierarchy has not been rendered completely.

watch on datasmith runtime actor