Is there anything you need to do to make sure you get the pet slot? I've read this question a few times, but all times it's about users with more then 10 pets (I only have 5) and the term GA is used a lot. What does this stand for? The more times I try to figure out this question, the more confused I get :P

GA stands for Gold account. We used to have to have a gold account activated to get 5 extra pet slots. Now however we get ten base slots free. Your account should say 5 of 10 pet slots used now. After Thursday, if you completed any quests, it will say 5 of 11 pet slots used.

Thanks :) So I can get another pet without trouble tomorrow?

Definitely. Since you only have 5 pets currently, you can get 5 more new pets right now. Tomorrow you'll get one more on top of that. for a total of 11 pets.

Thanks a lot for your help! :D