Chickens aren't genetically programmed to lay on the same day as others their ages, even if they are the same breed or variety. Each one has it's own internal schedule and nothing we can do can change that. All of the things you are doing are the best way to have healthy, happy chickens but do not guarantee an egg a day per hen. I have 3 Red Sex Links among my flock of 10 assorted chickens, for example, all the same age, bought from the same place. One started laying when she was 19 weeks old. Another waited until she was 25 weeks, and the last one was 3 weeks after that. So there's no need to worry that you are doing something wrong, or that there is something wrong with your girls. Also remember that the shorter days slow laying down - that's the way Nature designed them and although some will lay all through the winter, a slow down is perfectly natural and nothing to worry about as long as you know that they are healthy.
The most difficult word for a chicken owner - me especially - has to learn to hear with a smile is "patience." I have none, but my chickens try what little I do have to the max. It was that way waiting for them to arrive, to feather out, to go out and live in the coop and learn to roost, to start laying, and finally for the broody to hatch out the eggs I gave her. I've said it before and I'll repeat myself.....This chicken raising stuff would be a lot easier if they would read this forum and the books!
