ArcPy Export after Refresh.

I'm using ArcPy 10.1 and the mapping module to export my layout(s) to a png. I have several layers that I loop through to turn on and off before exporting. I also switch between different bookmarks before exporting. Unfortunately, the export occurs before the refresh/drawing is complete. In .NET I could listen for the draw event to complete before exporting the layout. Is it possible to do something similar in ArcPy?

It looks like creating an ArcPy extension might be one route, but I don't know if those events will tell me when the draw is complete.

Thank you!

Regards,
David