Hey,
you can add a jquery trigger event for this task. It's not a perfect solution because you need to use a static time interval and this can cause issues (e.g. if the client js code processing is too slow, etc.) but better than nothing. Open up js/avia.js and replace:
avia_item_fade({items: '.preview_image', hover: '.post-entry'});
with:
avia_item_fade({items: '.preview_image', hover: '.post-entry'});
setTimeout(function () {
jQuery('.hide_content').trigger('click');
}, 600);
You can replace 600 with an higher or lower value - however lower values may cause problems (because the gallery function requires some time for the initialisation).