Awesome pictures! I hope mine will be coming soon- I ordered six.
For what it is worth, when I hatched my Black Copper Marans I noticed after the first week or so that the ones that ended up being females had more pronounced tail feathers, while the males just had fluff back there for the longest time.
I got that advice on how to tell gender from the lady at Mesilla Valley Feed, where I get all my chicken feed and related products. It did prove true with the Marans.