it wont make a difference as they will known something is up with that many orders (unless the dont work on sunday or something) Also there is no need to worry, as the worst the could do is cancel your order.
However, just remember your money is charged. Which means if they cancel the order in 10 days, they will be holding that money for 10 days. Now if they got thousands of orders, they are holding thousands of dollars for as long as it takes for them to cancel the orders.