How old are they in weeks? I find that sometimes one person's idea of "8 months" can be =/- multiple weeks when compared with the "8 months" of the next person and with things like onset of production a couple of weeks can make all the difference.
Your breeds of choice are not particularly fast maturing birds. Are your Ameraucana true bred birds sourced from a reputable breeder or are they "Ameraucana" as sold by most commercial hatcheries which are, in fact, actually Easter Eggers? This will play into point-of-lay as produciton bred birds would be expected to lay sooner than lines of breeder bred birds that have been bred for primary traits other than pure produciton of eggs.
My experience has been that for pullets that first laying cycle is much less dependent on lighting - the supplemental lighting is more beneficial with inducing winter laying in the subsequent laying cycles of mature layers.