As TNS_2 said, Verizon will install everything, if you want them to. You may not like how they do it, however.
If you want to be sure everything is installed the way you like it, it does make sense to prepare ahead of time. The ONT will be installed near where the fiber enters your premise. This is usually, but not always, where your utilities enter now. If you don't already have fiber, it will be layed a few days before the install.
The ONT may be installed inside or outside your home. A power supply with a battery backup(*) unit will be installed inside. It needs to plug into AC power. A cable will be run from the power supply to the ONT and can be quite long. If you can find a location inside that has AC power and is close to where the fiber is, you can ask for an inside install. I prefer inside installations as it improves reliability by reducing the environmental stress on the ONT and eliminates a big ugly box on the side of the house.
In addition to fiber and power, the ONT connects to your home using twisted pair for phone coax for TV and internet, or cat5 Ethernet for internet only. Coax is used for internet when TV is installed. For an internet without TV installation either coax or cat5 Ethernet can be used. You should ask for cat5 Ethernet. This will allow you to easily use another router should you not like the Actiontec Verizon provides. If coax is installed, you pretty much have to use the Actiontec router unless you want to build a complicated network.
As the connection from the ONT to the router is either coax or Ethernet, it can be as long as you need. Verizon typically does not pull wires through walls, or does so for an extra charge. If you can install the wires yourself before the install, that would be good.
(*) Verizon currently is not supplying batteries free of charge on new installs. You can find them online for about half the cost of buying one from Verizon. While you don't technically need one for internet only, it is good to have.
Good Luck.