Not working on my site

I have installed the plugin – all looks straightforward.
I really would like it to delay the loading of the Google reCaptcha until the user is thinking about submitting a form.
I have added the keyword:
recaptcha__en_gb.js
to the ‘include keywords’ and set the delay to 10 seconds.
The file appears faster than that while page is still loading.

This is on a dev site with no cache or Autoptimize or Asset Cleanup running.

I have also tried with a js file from the host domain – using both filename and a unique phrase from the js itself and still nothing happens.

I think the plugin is a great idea and would like to persevere with it.

Is it something to do with running the page with the developer tools open in the browser? If so, how can I tell that it is working?

What could I be doing wrong here?
Thanks