function this_plugin_first() {
	// ensure path to this file is via main wp plugin path
	$wp_path_to_this_file = preg_replace('/(.*)plugins\/(.*)$/', WP_PLUGIN_DIR."/$2", __FILE__);
	$this_plugin = plugin_basename(trim($wp_path_to_this_file));
	$active_plugins = get_option('active_plugins');
	$this_plugin_key = array_search($this_plugin, $active_plugins);
	if ($this_plugin_key) { // if it's 0 it's the first plugin already, no need to continue
		array_splice($active_plugins, $this_plugin_key, 1);
		array_unshift($active_plugins, $this_plugin);
		update_option('active_plugins', $active_plugins);
	}
}
add_action("activated_plugin", "this_plugin_first");

http://wordpress.org/support/topic/how-to-change-plugins-load-order

Change Order that Wordpress Plugins are Loaded (Load First)

php, wordpress, array

PHP