Hi Michael Koelbl,
Thank you for contacting syncfusion support.
Our HTML to PDF converter could not automatically detect with the document ready state. However, we can achieve this manually by using window.status. We have already implemented a support for HTML converter to hook on the window.status, once it is set to completed the loading stops and start converting to PDF.
How to use it:
1) In the HTML document change the window.status to completed once HTML is loaded.
2) For Google maps, please check can you trigger an event once the maps are loaded and set the window.status as completed.
3) When the window.status is changed to completed, HTML converter will stop loading the HTML and process for PDF conversion.
I have attached simple Window status sample and input HTML for your reference.
Please let us know if you need any further assistance on this.