how do i claim my collectors edition mini pet?

title asks the question

how do i claim my collectors edition mini pet?

Once you have the cd key from the magazine added to the account, and Nightfall goes live. Enter Elona and type /bonusitem. This will activate the quest to get the minipet for Nightfall called broken toy I believe. Complete the quest and minipet will be your reward

this is for the magazine pet, not for the nightfall collecters addition pet :/

In that case from Wicki -

It has also been announced that contained in the Guild Wars Nightfall Collector's Edition will be an access key to acquire a Warmarshal Varesh mini-pet.

If it doesn't just appear after entering the key, /bonusitem was also used for getting the Factions Minipet. And I would gather you'll have to wait until NF goes live on Friday

You'll likely have to wait til the game goes live to get the pet....

Actually, it's going to be linked to the Nightfall Collectors Edition key. So when the servers go live, the first character you login to (with a free inventory slot) will get the minipet.

NB. There is no extra key in the CE.