Regular occurence here...
Working in a school with dozens of pupil iPads lockouts happen frequently, we can clear the passcode via MDM(Mobile device management) while the wifi's connected and then via an ethernet dongle but once it says 'Connect to iTunes' thats it... time to recover from a backup :( the longest I've seen is 1hr prior to the itunes message.
When they've managed to sign out of iCloud 3+ months ago things get REALLY interesting!