They will stay kind of bald looking, or thin, under the wings. You said your coop won't be ready for two weeks. They will be ready for it by then; they probably are now.
You need to turn the heat lamp in the bathroom off, now. They only need it for the first 4-5 weeks at indoor temperatures, and besides, you want them to be accustomed to not having external heat when they go out. You should also start taking them outdoors for short periods if you can. You can set up a small temporary pen with most anything; even half an hour is worth the trouble, longer if you can. If they run around, they are warm enough. If they immediately huddle together, they aren't. I would bet good money they will wander around, or run around, start pecking and scratching the ground, etc.
They won't need a heat lamp in the coop. Really. Not unless it gets around 25 below.