I got these chicks on Thursday, March 17th. At that point I believe they were already a week or so old. I believe they are all pullets as well. Anyway, I have some theories as to what breed they are (Wyandottes for the black ones and either Buff Orpingtons or maybe Red Sex Links for the yellow/red ones). I have 5 of each, let me know if you need a better picture to get an idea on the breed.
Looking forward to hearing what you think!