From the Pre-Order FAQ 20 Jan update:
http://forums.riftgame.com/showthread.php?19289-Rift-Pre-Order-FAQ-UPDATED-1-20-11
Are pre-order items usable during Head Start?
Yes. All of the pre-order items that you receive will be available to you when Head Start begins.
Trion does have the occasional brain fart from time to time but they fix em pretty quickly.