When & How do I prepare Pullets for Egg laying?

First time chick raiser, here! Our chicks are 11 weeks old. My son found an egg under a tree where the chicks usually hang out, but I suspect the egg is really from a laying hen, not the chicks. (we got a grown quartet from a farm, and several chicks this spring) BUT this brings me to think, when will they lay eggs, and how do I teach them?
The pullets have not been accepted into the quartet's flock. I don't foresee them learning from the other hens, since they chase them away. The pullets have been fully integrated into the henhouse at night for 2 weeks now and they sleep separate from the hens by choice on the roost. The first week or so in the coop at night they were locked in their crate for safety, and allowed to free range by 8 weeks.

We have 8 nest boxes in the henhouse. The pullets rarely go in the coop except to sleep or when they see me refilling food there. All of them are free range birds. Suggestions welcome please!