With so many Xbox One’s trying to download the day one system patch at one time, there are bound to be issues. With that in mind, Microsoft have taken steps to ensure disruption is kept to a minimum by releasing the patch early for download to a USB stick.
The Emergency Offline Update is available now and can enable those who wish to, the opportunity to get the system update ready onto a USB stick, before firmly planting said stick into the new console once it is in your hands.
All you’ll need is a USB stick, a PC with a USB port and most importantly, an internet connection!
Full details and procedures were on the Xbox support site.  – Until they were later pulled by Microsoft anyway!
Good luck.
Source: CVG