We had two contractors responsible for our yardscape in the back yard; the first company came one day then never returned, after doing the rough tiering of the yard into 4
zones. As you can see from the before pictures //www.agardenersforum.com/forum/ubbthreads.php/galleries/377386/2013_Yardscape_Back_Yard_Befor.html#comments it's a visible change, especially for one day; but the time frame from Contractor A to contractor B is a period of May 20th till September 5th.
This is also the time period that the south neighbor was in the process of replacing their fence.