In the viewing box you can type in your server and see what realm firsts have been taken so far. Though there is a small delay on armory I think. So sadly whatever realm first you might still be after might be taken within the last update of armory. Good luck in trying to get it, if you figure out the one you want is still obtainable.
*EDIT*: Hmm, it appears the link doesn't really work. Oh well.