@cereberus have a look see here, https://support.microsoft.com/en-ca/kb/3095675
Looks like the cutoff date is actually the 20th? Sort of kind of?
Changing your scheduled upgrade
BeforeJuly 20, 2016 if you have a scheduled upgrade and you would like to change when it occurs, or if you would like to cancel your scheduled upgrade, follow
Starting July 20, 2016, you will no longer be able to schedule or reschedule the Windows upgrade. (You will still be able to cancel or upgrade now.) If your upgrade was already scheduled, when you open the Get Windows 10 app, you will see the scheduled time and options to Cancel scheduled upgrade or Upgrade now.