I hadn't thought of heat but that's a good point. Ok, I can do the fence walking. I had two reasons for not wanting to turn them out until daybreak. The first as you said, I want them to see their new environment and secondly, I know this sounds bad but I want pictures:')
If you walk the whole fenceline they can see the whole perimeter, have seen the whole scene, and are a lot less likely to just bolt like they are a loose horse getting away with something when you turn them loose. It takes the excitement down to a safe level.