How do I get the 'Show On User Exit Attempt' Functionality to work immediately, without it

In the Add Ons, there's an option for 'Show On User Exit Attempt'.

This is a great feature and concept.

Unfortunately, it cannot be triggered immediately due to this issue: when 'Pop over appearance delays' is set to 'immediately', it shows when the page loads — instead of immediately when the user goes to leave the site.

And if I use the delay (1 second or more), the user will have most likely exited the page before it pops up.

How can this be fixed?