Every week is way weird - people shouldn't be affiliated with anything if they're that scared that they might reveal their identity.
Kiros had the same philosiphy about not changing your name ever, but guess what he did? He was
Kiros72 in September when I left...when I came back to the site in December, he was just Kiros O_o
I don't see a reason why it should be 3 months. Some people might join and think 'damn, what a stupid username' and then want it changed. Plus, it is advised that you put your last username in your sig (like in little letters "Formerly know as Apocalyptic_Storm" or something else)
The Admins reccomended people would do that, but they never enforced it