Dear Lisa,In Irish, crann tarra could be translated to mean a tar pole; and besides, there's already an excellent Irish band by the name of Crann. If you're going to be playing to mostly English-speaking audiences, I'd strongly suggest that you give your band a name in English, so your audience will be able to easily remember and pronounce it.
Now that I think about it, 'By Monday' is way too close to 'Till Tuesday', so scrap that one. Stick to something with three syllables, in English, and I think you'll be happy.
-- Áine