Software update needed to set up your Nexus 5
Let's assume that you have your new Nexus 5 in your hand and are setting it up. There is something you should know. An internal LG document reveals that during the set-up process, the phone will prompt you to download and install a software update. Without this update, your new pride and joy will not work. Apparently, to avoid a repeat of last year's chronic shortages with the Nexus 4, LG built initial batches of the phone before the software was complete. As a result, some of the handsets being shipped do not have the final version of Android 4.4 installed.
Based on a Nexus 5 set-up done by U.K. retailer Clove, the size of the update is 139.3MB (ignore the higher number on the screenshot in the slideshow below), although that figure could be different based on your region and your carrier. A download of this size could consume some of your precious data. A pop up box will give you a warning and will also apparently give you the opportunity to hook up to a Wi-Fi signal during the set-up process.
source: LG via Clove
Just remember that you will need to install this update to complete setting up your Nexus 5, and the phone won't work without it. Overall, it is just a minor nuisance, but one that you should know about nonetheless.
source: LG via Clove
Things that are NOT allowed: