Pasted

<script>
jQuery(document).ready(function($) {
    "use strict";
    
    /* change the calendar start day when date field receives foucus */ 
    $('#field_your_date_field_id').on('focus', function() {
        
        /* apply the radio button's value to the firstDay option */
        $(this).datepicker('option', 'firstDay', 1);
    });
 });
</script>