So having started the game at launch on my main account, I am eligible for my five year reward today, per the MOTD in game. I hit the /claim, and moused over the reward, hoping to see a listing of the item before I decided if I needed it in my bag. No list. So next step, since it reads “one per character” was to claim. Nothing. I looked in my window to see what I received and got the message “You cannot consume this item.”
A mystery. Or a bug. Wasn’t the four year reward fubarred too?
I have to add an edit here–I logged on at 6 am CST today and saw the “You may now claim your 5 year veteran reward” message in the MOTD. They have now changed it to reflect the Shadow Odyssey launch as the time for claiming said reward.
Trot Line 
Five year rewards will be active when the expansion goes live next week!
It will show up on Tuesday along with the game update that accompanies the expansion.