Are you supplementing light in the coop? If not, you may not see these young pullets reach point of lay until the days begin lengthening again, sometime after the new year. It often requires exposure to at least twelve hours of light per day to stimulate the egg laying hormones. It doesn't require much wattage to achieve this, even a 60 watt bulb will do.
If you do supplement light, it's best to set it on a timer to come on two hours before sun rise.
Salting the nest boxes with some fake eggs is a great way to get the hint across that these places are good egg laying spots. Even though they may not be ready to produce eggs right now, they may start exploring the nest boxes and playing house in them, all normal learning behavior.