Okay, so it turns out they're only about 15 or 16 weeks, and the guy had got them mixed up in his head with their parents.
To be honest, I had guessed them to about about 3 or 4 months, but I'm rather unfamiliar with Araucanas so when he said they were older, I started freeking out and thinking, "Wait! Maybe I'm wrong! I don't know anything about this breed other than the colour of their eggs! Maybe there's something wrong with them! Maybe I'm just rubbish at judging chicken ages! Are they ever going to lay?"
Sigh. All's well that ends well, I guess, and I suppose I can look forwards to eggs in about two months.