Since the whole thing could take few a hours, and you'll have to keep Drive active and on screen the whole time, Google advises you to plug your phone in and connect to WiFi. Now, you might not ever put this to use if you got a Pixel and the Quick Switch Adapter that comes with it, but it sure sounds useful for other Android devices. Just don't forget to switch off iMessage before you leave.

Give the gift of @Android. Drive now makes transferring photos, videos, contacts & calendar events easier than ever. https://t.co/xZpaA3Zmgq pic.twitter.com/TRdH4AYEKd — Google Drive (@googledrive) December 13, 2016