Is it possible to perform initial setup of my Xbox One without an internet connection?
No, you must be able to connect to the internet to perform the initial setup of your Xbox One console. This is required to create and sign in to a new Microsoft account, or sign in to your existing account. Once this is done, you can safely disconnect the console and use it in offline mode for as long as you like.
If there is no internet connection at your location, you can either try connecting it at someone else's house, a public connection, or to a mobile hotspot, such as your phone.