Hey Greg,
You can do that. There is a callback built into the slicknav script that fires once it’s been assembled. You’ll need to edit the custom-js.php file that’s in the “includes” folder of the theme. Find this spot:
// Slicknav
jQuery('#primary-menu').slicknav({
label: '<?php echo of_get_option('mobile_navigation_name','') ?>',
prependTo:'#side-menu',
allowParentLinks: true
});
and replace it with this:
// Slicknav
jQuery('#primary-menu').slicknav({
label : '<?php echo of_get_option('mobile_navigation_name','') ?>',
prependTo :'#side-menu',
allowParentLinks: true,
init : function( autoopen ){}
});
jQuery(function( autoopen ) {
jQuery('#primary-menu').slicknav('open');
});
Then save your changes. You can read up on the script at https://github.com/ComputerWolf/SlickNav
Hope that helps out,
Bill