When do chicks become pullets? I really don’t know for sure.
Chicks are these balls of fluff. They quickly grow wing and tail feathers. Body feathers push their way out. The fluff disappears as dust.
Not all of the fluff disappears. Some is persistent. The feathered out chicks have these ragged bits of fluff sticking out in odd places.
These chicks are still chicks. They are small and peep. They still like a bit of heat at night.

Once chicks have feathers, staying inside is not popular. Rainy days keep mine inside. They sit up on anything tall to look out the windows in the door.
Sunny days are a delight. The bottom door opens and a new world stretches out in front of these chicks. The chicks line the door sill, heads and necks twisting and turning as they look around.

By the second day the chicks are waiting for their door to open. They generally stay inside as I fill feed trays, but don’t stay there long. Grass is much superior to chick feed.
A week later I make sure I am not standing in front of the chick door when I open it. Twenty-two feathery bullets shoot out. The chick yard is too small.
There was a time when I would let older chicks out into the grass. Grey foxes now live across the street. Quarter grown chicks are snack size.
Now I put up a ring of chicken wire. The chicks come out into a larger yard only when I am working close by. Moveable electric fence posts make moving the wire into different shapes and areas easy.
Now six weeks old have my chicks become pullets? They are almost half grown. They fly across their yard. They chase bugs as well as eat grass.

These birds still peep. I think they are still chicks.
In another week or two, these pint sized chickens will start clucking. They will not be happy in the larger yard. Already they cast longing eyes at my garden. There is an invisible “Chickens Keep Out” sign, except they can’t read.
I think my chicks become pullets when they start clucking.