Charge later fees to contractors for not finishing on time

[Tracy Hightower]

I've recently started moving into a new market and the contractors are known for not finishing the jobs or taking an advance and running off. To compensate I was thinking charging $100 for each day over (excluding extreme weather and unknowns that popped up during rehab). I also considered a bonus to finish early. Either way, their estimate to complete the job would probably be longer than necessary just to favor them. I DO pay a certain percentage a couple times during rehab (but after something is completed) and the largest amount at project completion.

I was wondering what others do, if there is a recommendation, or something else to consider.