I call that two to three week old age the dinosaur phase. And just let them run out of food for a bit, then put some in there. More like velociraptors.
I have not had your breeds, but in another week or two, expect them to pretty much be covered with feathers. It will not be their final adult plumage and their shape will still be chick and not adult chicken, but they will look a lot better. It will vary some by breed, climate, feeding regimen, and who knows what else, but somewhere between 12 and 16 weeks, they should look a lot more like the adults. They will go through their last juvenile molt during this time period and put on their adult plumage. The colors and patterns won't change that much unless there are some recessive pattern or color genes working, but some pattern change is possible.
It is possible that a chicken can start to lay as early as 16 weeks. It is highly unlikely but possible. It is also possible that a chicken will wait for 7 or 8 months or even longer to start laying. It can vary a lot by individual. I don't know about true Araucanas, but if they are really the EE's which most hatcheries sell, they have a reputation to start laying a bit later. Some of the ISA Browns could start laying fairly early. I'd suggest at 18 weeks have the nest boxes open with fake eggs in there to show them where to lay. A week or two earlier would not hurt, but I'd set 18 weeks as a deadline to be ready.
I have different breeds than you and I had twice as many pullets. My first one started laying at 18 weeks. At 20 weeks, two more joined in. At 22 weeks another two joined them. It kinda progressed that way, a few starting, but the rest waiting. And they do not necessarily lay every day.
Some people feed extra high powered feed to try to start them laying as early as possible. I prefer to keep them on a regular diet so the pullet's body has time to mature and her egg laying factory has time to develop. I get fewer of those weird first eggs and there is less chance of her getting eggbound or prolapsed.
Good luck!!