I'm assuming you mean to stay in the coop vs the brooder. In my opinion, it's about age (feather coverage) and temperature combined. When first born they have no way to regulate their own temperature, so they need to be kept around 95. As they feather in, they can stand cooler temps till around 5-6 weeks when they can take 60-65.
I put my chicks out at 4 weeks with a heat lamp in the coop till 6 weeks old. I also live in the south so temps were part of it.
In summary - keep them kinda warm till nearly all the way feathered, which is usually 6 weeks or so, or when nighttime lows are in the mid 60s.
Also remember that every bird, flock, setup, and situation is different, so you have to do what you are comfortable with. Have fun and good luck.