How many customers placed orders before George?
SELECT count ( T1.customer_name )  FROM customers AS T1 JOIN orders AS T2 ON T1.customer_id  =  T2.customer_id WHERE T2.date_order_placed <  ( SELECT T2.date_order_placed FROM customers AS T1 JOIN orders AS T2 ON T1.customer_id  =  T2.customer_id WHERE T1.customer_name  = 'George' order by T2.date_order_placed LIMIT 1 ) 
count customers who placed orders = COUNT(customer_name); before George refers to comparing the date_order_placed with George's first order date;