Bethesda have confirmed in a tweet that Fallout 4 will be available to preload in advance of its launch. This means that when midnight strikes you will be able to begin your quest for survival.
We can confirm that #Fallout4 will have pre-loading on Xbox One, PS4, and PC so you have a few days to download the game before 11/10
— Bethesda Softworks (@bethesda) October 26, 2015
The size of the install hasn’t yet been confirmed for the Xbox One. It has however been revealed that the PC version of the game will require 30 GB of free space. It would be safe to say that the Xbox one version will require a similar amount of space on your hard drive.
Fallout 4 has been heavily preordered with many versions of the release selling out quickly but you still have time to preorder and preload before the launch at midnight on November 10.