The installers usually call me the day of the install. The last installer called right at 8:00 AM for a scheduled 8AM-Noon install time. If it's a PM install I think they have usually called late AM.
Even so, problems still creep up. He had originally planned to install the 1000.2 (I think) but 129 wasn't picking up properly due to a LOS issue. He installed 2 Dish 500's instead to pickup 110/119 and 61.5. I glimpsed into his truck at one point and he had quite a bit of supplies to cover many issues that might pop up.
You'll probably be alright, so try not to worry. Besides, there isn't a whole lot you'll be able to do about it until the installer calls or shows up.