When will my whole flock lay???

I have one girl, a Production Red, who began laying over a month ago i'd say she lays around 5/7 eggs a week. However, I have 5 other hens whom have yet to lay their first egg! Yes, they are all different breeds, but they are roughly the same age a week apart or so. I have a French Black Copper Maran, a Buff Orpington, an Americauna, Barneveldar, and a mix breed between an Americauna/leghorn. They are all 5-7 months old, most likely 6-months, when will the others begin to lay? They are all pretty big hens already.