shirt can't be registered until adoulin is completely live anyway.

playonline: On March 26, 2013, the FINAL FANTASY XI: Ultimate Collection Seekers Edition will go on sale and those who purchase this special edition will also receive the Chocobo Shirt in-game bonus item. Please note that registration of the Chocobo Shirt campaign code will not be available until Seekers of Adoulin becomes playable.

*The specific time when Seekers of Adoulin content will become playable will be announced at a later date.

elsewhere on the forum: "my code says its already expired."