My 2 oldest hens just started laying this week. One lays sometime around 11 a.m. and the other one jumps into the same box at 12 noon. I watched #2 today---run everyone away from the coop and sing her song.
Then, I check and she left me a lovely light green egg. YAY!
My Lavender Orpington & Barred Rock started laying between 7-8 pm. It seems when I let the hens free range, one or two decide it is a good time to use the nest box that all 15 fight over.