chick coop

It's best to wait until they are around 5-6 weeks old. They get cold very quick when they're very young still. If it's warm and you can put them in a sunny spot, you can put them outside during the day, in the afternoon maybe?

Mama hen would have them outside at a couple of days old. Just keep an eye on them and bring them in if they act cold (huddling together and peeping). Also they should have access to grit in some form if they are outside eating grass and bugs.

If you mean moving them to a secure coop with a heat source as they would have in a brooder then any age would be ok. I wouldn't rely on them being able to find the heat in a coop if they have free access to the outside though.

If you have other chickens I would wait till they are much older to introduce them to the flock. I guess

I just don't quiet understand the question but hope I've answered you.

Mine turned 3 weeks this wednesday , and they have been nothing but trouble!  Baha, we have them in a corner of the coop, segregated away from the ''older'' chickens. The older chickens just do not like the little girls, always trying to get at them, and the little girls try to see the older chickens because they are so interesting; not a good combination. So at three weeks they are fine with a heat source at night; being with older chickens.... wait until they can stand up for themselves.

There isn't a single answer that is right - it depends on a multitude of factors.  As a PP said, when a broody hen hatches chicks, they are outside from day 1.  However when raised in a brooder the heat lamp is a substitute for the hen so unless you can move the heat lamp outside, there is less flexibility.

I've never kept mine inside more than four weeks - and that includes a batch I hatched in January!  They were outside full-time by the time they were four weeks old.  I've even heard that keeping them in longer than that is doing them a disservice as they don't develop their feathers as well. 

Here's what I do: for the first two weeks they are inside.  Period.  In their third week, I start looking for nice days (I raise my chicks in Spring so some days are cool, others warmer.  By "nice days" I am looking for days of 70+).  The first nice day, I wait until early afternoon, put them in a cat carrier, and take them outside for a couple of hours.  Assuming the next day is similar weather-wise, I do the same but increase the amount of time to 3-4 hours.  Continuing like this, on each successive day, they go out a little sooner and stay out a little later.  Around the end of their third week, I turn off the heat lamp inside at night.  By the middle of their fourth week of life, I look for a night that is forecast to be mild, and instead of carrying them back inside, carry them to the coop and let them spend the night in there (still in their cat carrier so they are safe from the big girls).  For about a week, they sleep in the coop in the cat carrier.  At this point I consider them transitioned to outside, and put them in my grow out coop until they are big enough to transition to the big girl's coop.