Well, darn. I deleted the message I just typed out.
I had said that my chicks were in the coop around three weeks, and they chose to sleep away from the heat lamp around five weeks (I think). I do remember that it was off before six weeks. I have to tell you that was a big relief. When they choose to not use the lamp, there is no anxiety about whether or not they're okay.
When I get back from the funeral, I plan on cleaning the coop so I can put the ducklings out there. They seem to already be okay with my 65° bedroom. Being that ducks grow so fast, it's not too surprising. Of course, they will also get a heat lamp until they decide they're done with it.
Yeah, I know 7 week olds may not need any heating source any more, but these girls are so spoiled and prefer to stay warm. Even I turned off their heating pad, they still sleep under it at a 65 degree room temperature. DH also insulated their coop walls. With all the open ventilation under the roof, I'm not sure the insulation will help at all. Well, as newbies, we are always worried too much.