As you can see from the replies here - we all do things differently either through choice or necessity (e.g the size of your coop etc). I prefer to let my alpha hen hatch, and i leave her in her nest until the chicks are born, then its down to a small broody coop. After 1-2 days, i leave the door to the broody coop open, so mum and chicks can do their thing. Since they are in the main coop, it seems that the rest of the flock is totally fine with the little ones and they only seem to start teaching them chicken manners when they get to around 4 weeks when the little boys seem to think they are already men! With my first hatch i was overprotective of the chicks, but these days, i just let them get on with it (I made this decision when i found that a couple of escape artist chicks had escaped the broody coop and were happily out with mum with the rest of the flock).
Good luck in whatever you decide to do.
CT