I'd really just wait until the installer shows up. As mentioned it all depends on the installer on how good he/she wants to make it.
If you have the wallfish already setup with a string to pull, ready and open stuff out of the way for the guy then all he has to do is put a good head on the fish line and go from there. Have the tv's pulled back from the wall, area clear.
I go out of my way on alot of jobs, but there have been times where quickest and easiet came first.
It's not fun or convienient when showing up to a job, you have to park in the street walk 200' with your tools, you get to the home, customer takes 10 minutes to answer the door, go inside have a little dog come bite you at the ankles, kids running everywhere, personal items all over the floor, animal droppings with mold on them (famous words I keep telling the boys to pick this up) then in the middle of the job, please move your vehicle my daughter needs to get out, etc.
Use your judgement make it easy on him/her, especially time wise and you never know. Good things will probably happen.
When I get back early and have time I pre-call the customer the night before and give them a heads up on what needs to be done, to make things more efficient and the scheduled work comes out better majority of the time.