Change status Woocommerce

function set_order_status_when_tim($order_id){
  global $woocommerce;
  $tim = $needs_timologio = get_post_meta( $order->id, '_billing_needs_timologio', true );

   if($tim == 1) {

   $order = new WC_Order( $order_id );
   $order->update_status('on-hold');
   }

}
add_action('woocommerce_thankyou','set_order_status_when_tim',10,1);