Open first item in accordion on page load

Got a sidebar filter in my site that has accordion headers. I would like to be able to have the 1st item always open (/expanded) with an option to do the same with the 2nd one.

This is the js: (Its a script from a shopify app called Power Tools)

<script type="text/javascript">
  $(function(){
    $('.filter-menu h4').on('click', function(e){
        $(this).closest('.filter-group').not('.has_group_selected, .refine-header').toggleClass('expanded').find('ul,.filter-clear').toggle('fast');
        e.preventDefault();
    })
  });
</script>

Here's a link: https://www.zoobgear.com/collections/punching-bags

(trying to make the category item always open)

Any suggestions? maybe altering the script would do the trick...?

Thanks a ton for any advice!!!