Magento 1.9 observer check if customer has at least order with complete status - magento-1.9

Question

i want to use observer to check if customer has at least one order complete to change order status to processing ( so when customer press on place order then make check if has any order complete then change status from pending to processing )
this is my code but this edit status to previous order not existing order
class ChangeOrder_Observerstatus_Model_Observer {
public function autoOrderevent(Varien_Event_Observer $observer)
{
$order = $observer->getEvent()->getOrder();
$orderId = Mage::getSingleton('checkout/session')->getLastRealOrderId();
$custAdmin = Mage::getSingleton('customer/session')->getCustomer();
$custAdminId = $custAdmin->getId();
$order_collection = Mage::getModel('sales/order')->getCollection()
->addFieldToSelect('*')
->addFieldToFilter('customer_id', $custAdminId)
;
foreach($order_collection as $order)
{
if ($order->getState() == "complete") {
$Is_Complet = true;
}
}
if($Is_Complet)
{
if(!Mage::registry('prevent_observer')):
Mage::register('prevent_observer',true);
$orderId = Mage::getSingleton('checkout/session')->getLastRealOrderId();
$order = Mage::getModel('sales/order')->loadByIncrementId($orderId);
$order->setState(Mage_Sales_Model_Order::STATE_PROCESSING, true, 'Payment Complete.');
$order->save();
endif;
}
}
}

Answer 1

Use event "sales_order_place_after". Compared to other checkout events it fires in any case when order has been placed.
Your described logic has to be implemented in observers method body.