How to use wp_days_ago_v3() with post id

What you describe isn’t possible with the current version of the plugin. But if you replace the wp_days_ago_v3 method in the wp_days_ago-core.php file, it should work – the first parameter is the id of the post or comment you want to use the plugin for.

Please note, however, that this code is completely untested (I don’t even know if it compiles), and it will be overwritten you update the plugin from the WordPress admin interface in the future.

function wp_days_ago_v3 ($theId = null, $stopUsingAjaxAfter = 0, $showDateAfter = -1, $showDateFormat = null, $showYesterday = true, $context = 1) {
	if ($theId == null) {
		$id = ($context === 3 ? get_comment_ID() : get_the_ID());
	} else {
		$id = $theId;
	}

	if ($context <= 1 || $context > 3) {
		$the_time = get_post_time("U", true, $id);
		$ajax_wait_time = get_post_time("H:i", false, $id);
	} else if ($context === 2) {
		$the_time = get_post_modified_time("U", true, $id);
		$ajax_wait_time = get_post_modified_time("H:i", false, $id);
	}  else if ($context === 3) {
		$the_time = get_comment_time("U", true, $id);
		$ajax_wait_time = get_comment_time("H:i", false, $id);
	}

	if(gmmktime() - $the_time > $stopUsingAjaxAfter) {
		echo wp_days_ago_internal_v3($the_time, $id, $showDateAfter, $showDateFormat, $showYesterday);
	} else {
		echo "<script type=\"text/javascript\"><!--\n";
		echo "jQuery(document).ready(function(){";
		echo "get_wp_days_ago_v3(" . $id . ", '" . $the_time . "', '" . $showDateAfter . "', '" . $showDateFormat . "', '" . $showYesterday . "', '" . $context . "');";
		echo "})\n";
		echo "--></script>\n";
		echo "<span class=\"wp_days_ago\" id=\"wp_days_ago-" . $context . "-" . $id . "\">" . $ajax_wait_time . "</span>";
	}
}