limit nodes programmatically creating in period of time

Hi , I use custom code to create nodes programmatically , but i have have sql usage for nodes creating without delay or waiting queue
here is my code ( check the node title before create new node ) :
How i can add new conditions to limit node creation based on time ?

    $query = new EntityFieldQuery;
    $result = $query
       ->entityCondition('entity_type', 'node')
       ->propertyCondition('type', 'site')
       ->propertyCondition('title', $title)
       ->execute();

    if (!empty($result['node'])) {
        $nodes = entity_load('node', array_keys($result['node']));
        $query = array('destination' => "node/$node->nid");
        ---------------------
    } else {  
           $newnode = new stdClass();
           $newnode->type = 'site';
           $newnode->field_links['und'][0]['url'] = $title ;
           $newnode->title = $title ;
           global $user;
           $newnode->uid = 1;
           $newNode->format = 1;     
           $newnode->status = 1;    
           $newnode->promote = 0;
           $newnode->language = 'und';
           $newnode->revisions = NULL; 
           $newnode->changed = REQUEST_TIME;
           $newnode = node_submit( $newnode );
           node_save( $newnode ); 
       }