By default, it will show created date from the backend blog listing page, if you would like to show "published date", you can modify on this file ->
JoomlaFolder/administrator/components/com_easyblog/themes/default/blogs/default.php
//LINE 206
<?php echo EB::date($row->created, true)->format(JText::_('DATE_FORMAT_LC1')); ?>
// Replace with
<?php echo EB::date($row->publish_up, true)->format(JText::_('DATE_FORMAT_LC1')); ?>
Hope this help.