Adding jQuery Datepicker to Marketo Form?

Has anyone had success loading the jQuery Datepicker into a Marketo form field?

https://jqueryui.com/datepicker/#min-max

Because the form dynamically populates, the Datepicker script doesn't work. I want to use this script so I can set the selectable calendar dates 72 hours in the future. Unless that capability is available in Marketo somewhere.

My script:

<link rel="stylesheet" href="https://nation.marketo.com//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">

<script src="//code.jquery.com/jquery-1.12.4.js"></script>

<script src="//code.jquery.com/ui/1.12.1/jquery-ui.js"></script>

And then within my form call...

<script>MktoForms2.loadForm("app-sj02.marketo.com", "APPID", FORMID,

    function(form){

    $( function() {

    $( "#Lead_Source_Notes__c" ).datepicker({ minDate: -20, maxDate: "+1M +10D" });

  } );

.... rest of form code

I want the datepicker to apply to the Lead Source Notes field and it doesn't. Also tried it without the $( function() { in front of the datepicker form call and nada either.

It DOES work on a text field outside of the Marketo form if I do this:

<script>

  $( function() {

    $( "#Lead_Source_Notes__c" ).datepicker({ minDate: +3, maxDate: "+1M" });

  } );

  </script>

<p>Date: <input type="text" id="Lead_Source_Notes__c"></p>

So it's because Marketo is loading the form dynamically.

Any help?