You might want to lower the temperature to about 85F. The more feathers they get, the less heat they need. Also, do not buy a pre-made coop online. I bought one as a quick fix to separate my cockerel from the pullets and it has taken me longer to make adjustment to the pre-made pieces than if I would have just started from scratch. It's also less expensive. You have some time and there are great plans here on the BYC site. You might consider purchasing a brooder plate for your next batch of chicks. The savings on your electric bill will pretty much pay for the plate. I used the heat lamp with my first batch and it was OK. But I have noticed a big difference in the chicks I'm brooding right now with the brooder plate. They seem less crazy and are getting their feathers quicker. Best of luck to you.