This is where references can be a big help. Your contractor should be able to provide references that can attest to the professionalism of the crew that did the work, and also give you firsthand information regarding the details. If the installation requires more than one day, the crew should be there at the same time each day, no exceptions. If they cannot make it due to extreme weather or any other circumstances, you should be contacted at the time they would normally get started to be advised of this.