Do not use the open form function, but use a microflow where in the end you just open de form . You can then do all the things you like to do in the microflow before opening it.
Regards,
Ronald
You can use the microflow timer and set it to run once after a short time.
Try calling the MF via the API within the HTMLSnippet Widget (Javascript Content Type).
You can use Jquery and try something like this..
$( document ).ready(function() { mx.data.action ( { params : {actionname : "ModuleName.MicroflowName" } } ); } ) ;