Construction clean is the hardest clean to estimate. Much depends on what they are asking you to do (tasks) and the condition that the home is in when you start. All of these drive time it takes to do it. Windows, one or two stories? Condition? Hard floors- sealing/refinishing? Make sure that you have agreement on what is to be cleaned, how many times and by when.
One thing about construction clean- make sure you clean it once, have it inspected, then checked off as done. Fail to follow this and you will re-clean for free several times before you get paid. Trades come in after you clean then you get tagged to clean it again ( for free)