No, the contract for an online order is normally formed when the goods are dispatched, not when they are delivered.
From Amazon's terms of sale (which I'm sure you read if you've ever shopped with them, right?):
Your order is an offer to Amazon to buy the product(s) in your order. When you place an order to purchase a product from Amazon, we will send you an e-mail confirming receipt of your order and containing the details of your order (the "Order Confirmation E-mail"). The Order Confirmation E-mail is acknowledgement that we have received your order, and does not confirm acceptance of your offer to buy the product(s) ordered. We only accept your offer, and conclude the contract of sale for a product ordered by you, when we dispatch the product to you and send e-mail confirmation to you that we've dispatched the product to you (the "Dispatch Confirmation E-mail").