When there is a lighting rig, someone has to go first and someone has to wait. Very very often, a build day will somehow be conveyed to the camera department as a pre-light day. You will be told “the DP wants to come down and do a few tests” Next thing you know, sparks are turning up at 9 am while the walls are going up continually asking you when they can get started. Production seem to think that one completes small sections of the set, right down to the dressing which can then be pre-lit, before moving on to the next bit. Every effort needs to be made not to utter the words “They can come down and we will try and have something for them to look at by lunch” The producer hears “They can start at 9 am, we will have tea ready and some biscuits” Furthermore a normal problem is that if there is a large piece of rigging being slung over the set to hang the lights on, it takes half a day to rig and then light. This is assembled on the floor and so, it needs to be built before the set. Either allow the rigging to be done first and call construction late (up to 11 am without incurring overtime rates) then perhaps the lights are finished or perhaps not. A set not only needs to be erected, it needs to be painted twice before it can be dressed, no no rushing on sticking emulsion to everything if it was a slower build.