ours have been out in a cage in the chook shed at 3 weeks - now the weather is alot warmer!
Once they start showing feathers, the lamp goes off in the middle of the day... then most of the day... then all day... then we give them at least a few days & nights in the house with the window open.
Some days the shed has been warmer than the house! so no detriment at all to the chicks
It all depends on the climate outside - the first hatch were in alot longer, and yes, they make the room smell !!