Two weeks is a bit young for that temperature. I've put chicks out a bit older than 3 weeks when the nights get that low. They have a small protected shelter for nights and small pen days. What promotes faster feathering is if you've lowered the temp your brooding at inside. I start at 95F, measuring at brooder floor under heat lamp and lamp only one one end so they can self regulate heat. In three days I raise the lamp to get 90F then in week raise it to get 80-85F and so on. By third week I start to turn off the lamp for periods during the day and last few days before putting outside they have no additional heat. We keep the house at 65F 24/7 in spring during incubating and brooding. Don;t forget you can change the wattage of incandescent bulb to lower temp too.
In a nut shell acclimate your chicks and watch their feather growth, some lines of birds are slower to feather so would require longer brooding. Also watch how they behave with no additional heat or as you are lowering it. If they chirp a lot and huddle under the light then they are too cold and not ready for that lower temp.
