I have a Amercauna Pullet I don't know her age but still haven't received an egg! Today I was out cleaning the coop... next thing I know my rooster decides to mate with her. Should I be expecting an egg sometime soon?
Although the physical act of mating won't be what makes her lay, it's a good indication that she's reaching laying age when she accepts the rooster. Probably in the next week or two you'll find her comb reddening and an egg waiting for you.