Login to the Subscription Center and get them now :)

Serial numbers will be available on Subscription Center by the end of day. If you are listed as the Contract Manager or Software Coordinator, you can obtain your serial number and product key from Subscription Center under the "Coverage Report", found by clicking on the "Contract Administration" link on the left navigation bar. If you do not have access to the serial number, you can install and begin using the product as a 30 day trial until your serial number arrives.  

Software Coordinators will receive an email from Autodesk with the Product Key, Serial Number and Tracking Number when the box ships next week.

You may also want to update your FBX plug-ins. Something useful with FBX is the compatibility charts for Maya and MotionBuilder that talk about how data travels between the products.