It's always exciting to try to login to My Wallet with GA 2-factor authentication. Half of the times I manage to log in on 3rd attempt, some times after restarting the app on iPhone. Some times I get in from 1st attempt. And other times, like now, my account gets locked for 4 hours after 5 failed attempts.
Looks like the GA has serious time drift problems.
(At least I have access to my Wallet through the iPhone app, though it lacks custom send option for selecting sending and change addresses.)
Use Authy... it is MUCH better than GA:
https://itunes.apple.com/us/app/authy/id494168017?mt=8 Also if you have a Mac and Bluetooth 4.0 you can get their companion desktop app that will pair with your phone and mage the TFA much easier to use in all.