I started the blow drying when I first got them. 2 were a week old and 1 was only 1 day old. I know that young they can't self regulate their temperature. I'm not even sure when they are able to self regulate their temperature.
I won't let them in the water until they have their feathers. I will give them about an inch of water to dabble in. They will sit in it. Only when it's sunny and warm. I never dry them unless my daughter is "dabbling" with them and they get all wet. Here are some photos: