I bought her at TSC as a Cuckoo Marans, but some have said she is a Barred Rock. She was a few days old; and that was 8-12-18. She is 13 weeks old. When do you think she will lay her first egg? We live in central Florida.
She looks like a Barred Rock to me. Somewhere around 3 more months. It's hard to say. If she is a hatchery bird from my experience they may start a little sooner, if from a breeder maybe a little longer.
Same with Rural King. A few years ago I bought some labeled as Brown Leghorns and they turned out to be Partridge Rocks. I found a breeder eventually for my Brown Leghorns. As chicks they do look very similar.