A lot depends on the building and how it is wired. We had our house done last Saturday, and it took 5 hours. We had two crews, the outside crew of 2, and the inside guy. Our house was built in 1934; it is double-course brick with plaster interior walls -- almost none of the walls are hollow. If you are in a modern building with easily accessible cable races it probably won't take very long.
The first 2 hours was all outside. The first 30 minutes or so was making sure that the signal was available and just scoping out the project. In our case they had to run a new line from the main pole on the street to our home, as the old line was not capable of handling the load. (And we did have DSL before.) They also put in a new box as mentioned by a PP, and ran a new connection in from outside into our basement to a jack.
Then the inside guy took over. We have two TV's, and it is TV's that are the most time-consuming, according to the tech. We had DirectTV before, and he followed their wiring path, but had to pull a completely new set of wiring both upstairs and down.
All of this was approximately the first 3.5 hours. Up until this point none of our old equipment was shut down. After this he disconnected the old services and hooked up his new wiring, then got the receivers and modem unit out and plugged them in. After the physical installation he had to fire up each device and make sure that it worked.
FYI: Do not trust the tech to be sure that your phones are working correctly -- all that they will check for is a dial tone on the phones. What they will NOT do, we discovered, is wait to make sure that the sound quality is good. Listen to it yourself and be sure. After the tech left, having verified that we had a dial tone, I discovered that we had loud background noise on the line that sounded like helicopter blades interspersed with snare drums -- but yes, there was a dial tone somewhere in there, too. I had to call back during business hours yesterday to get their techs to reboot my modem and get the static off the line; that took 90 minutes and 5 phone calls to accomplish.