Well, I am a May 2017 Model S with AP2 ... I just requested the FSD upgrade and got a July 5th Mobile Service Appointment. Now, it just happened so I'm sure I'll get an e-mail telling me that it can't be done yet - but here's hoping.
I also saw some comments about why the rush to get the upgrade. In my case, my wife just got a Raven Model X .... her autopilot seems smoother and her sentry mode actually records (and she has working dashcam!). And just to rub the salt in the wound, she's got MCU2 and the new games ... I sure hope Elon was right about being able to upgrade from MCU1 to MCU2!