When can I kill the heat lamp?

I live in Florida. Our daytime temps have been running in the mid-to-high 70s, a bit warmer in the garage where my birds live. Nighttime temps are in the mid-to-high 60s.

They're 5 weeks old now and I've still had the heat lamp going. Do they still need the lamp, or can I turn it off? Should I leave it on at night but turn it off in the daytime?

I don't know what their behavior is like these days because I'm not out there All The Time like I was then they were tiny fuzzbutts, now I'm only out there a couple times a day to clean the pen and check food and water, and half the time I go out there and SOMEbird has escaped the pen (I seriously need to just give up on the lid!) and is walking around the garage.

 

I'm still building their coop. I'm working as fast as I can, but it's just me for the most part, and I can only do so much before my back gives out. I'm hoping to get their outdoor space finished within the next two weeks.

It'll be easier when the next batch of babies comes in August. Everything will be all set up, I'll just have to deal with the integration of new birds with the current flock after a few weeks. I'm building the pen big enough for nine, even though I'll only be keeping six. I ordered more than I needed to allow for losses, and if all of the new ones survive I'll sell the extras at auction when they get to point of lay.