I start interacting with mine right away, about the second day I have them. I sit by the brooder with my hand in it, resting on the floor. I mix up some mash snack (their feed, wetted with water to make a mash) and have a glob in my palm.
OOOO!!! Hand is big scary thing! Everyone run away!
Sit. Sit. Sit, very still. Eventually, one of the chicks will come check out the big hand thing and peck at it... and find... FOOD!!!
I did this 2-3 times a day. By the second or third day, they knew the hand held food and as soon as they saw it, they came running.
Change tactics. I'd put my foot in the brooder. Another big scary thing. But this one didn't have food, so we'll just hop on it and hop back off. Eventually, one will figure out how to climb up my leg. Momma jungle gym! Oh, what fun. Sitting on Mt Kneecap opens up whole vistas.
Things to remember:
They are prey animals, so anything coming down from above is instinctively scary. Reach in from the side, not down from the top.
Move slowly and let them come to you.
Food is a good way to make friends. Make up a few tablespoons of their feed as a mash. They love it! (It's your regular food, chicks!) Use that as a treat as often as you want.
I talked softly to them. "Safe with momma, safe with momma." I would very gently stroke their wings with the back of my index finger. No pressure, just a gentle stroke to get them used to my touch, and touching their wings, not their backs.