After you finish your last export, activate a Macro with a Periodic trigger of every 10 seconds that check the file count in the target folder. When the count does not change, the notify and deactivate the macro.
I believe the secret is to try again. It's what I do. If I can't do something, I have a go, knowing it will probably not work the first time. Then I try something different. And something different again. And I keep going. The benefit of this is that, along the way, I may have tried many different things and techniques that I end up learning more about a piece of software or a programming language without necessarily realising it at the time. So, often, though it may feel as if I put in two days' worth of effort to get one thing working, I've also picked up a bunch of stuff that makes my next task, and the task after that, so much simpler and quicker to do.
I know it feels difficult now, but if you persist, you will be glad you did.
Set a "folder changed" trigger to update a specific variable to the date/time whenever a new file is added.
Set a periodic trigger to save that the last new file date/time and compare it against the previous captured. If it's more than your window you're done, else save the current value
Running this periodic check every 10 seconds may be more than you need. Maybe you can enable it when you start the export process.
But I have to say, others have given you good hints. If you are having trouble understanding how to implement their suggestions (or mine) then you might need to start with simpler tasks first. I'm now able to create FAR more sophisticated macros than when I first started. You can learn how too.
i am not the one who opened this post... I am just a reader. I noticed that even with the kind of rude responses that the author post demanding for help you openly wrote a great guide for him. And of course... no even a word gratitude by the author just saying Thanks! So I am writing this for you Devoy, I want to thank you for being such a great human being, I wish the world has more of you around and this could be a great planet to live on... unfortunately I rarely meet people like you. Because people like you the human race become who we are now. Sadly, because the reality is the other way around, humans are in the path of distorting themselves. One more time, thank you for being yourselves. My two cents to this post.