I'm going to pick up some one week old black/blue copper marans tomorrow and curious to know if it is too early to be able to tell if they a roo or hen.
It wouldn't be 100% but roos might have a bit larger comb (not real likely at this age though) and males tend to have thicker legs. But truely at a week it's pretty much a crap shoot. Good luck though. If they're fbcms and you get an extra roo you can send him my way