It seems I have a couple of late bloomers on my hands. While one of my new chickens has been laying since mid-August, the other two have not yet started producing eggs.
At first, I thought the layer was Rita because the first few eggs were light brown and on the small side. The shells of the new eggs have darkened, though, and I'm now thinking Janice, my Cuckoo Marans, might be the layer. She's got her full comb and wattles and seems calmer than the other two new girls, which could also indicate she's the one making the eggs.
The only weird thing is that the eggs seem too small to come from such a big chicken. Janice is basically the same size as Tina, my Black Sex-Link, but the eggs are about 3/4 the size of Tina's eggs. The mystery will be solved as soon as the other two girls start laying. Hopefully, they'll get off their feathered butts and make some eggs soon.