The order date on an Amazon order is the time the customer purchased the order - not the time the order was completed. Amazon usually holds orders for a short time to verify payment and they will not include an order in the regular order reports until it is completed. In some rare instances, there might be multiple days between the order date and the date the order is reported on.
If you see an order that appears new and want to see when it was first reported on, you can go to Settings->Company Settings->(Company Name) ->Reports. Click on an order report run yesterday and view the report to see if that Amazon order number was included.