I received my VIN on 9/4 when I scheduled my delivery appointment for 10/1.
Last Friday 9/21 my VIN and appointment disappeared from my account; I emailed my delivery advisor with no reply.
Sunday 9/23 I got a call from her telling me my car was "arriving earlier than expected" and asking me to take delivery this week, presumably so it will contribute to Q3 numbers. Rescheduled delivery for Tuesday 9/25, and the new appointment appeared in my account with a completely different VIN.
Yesterday 9/24, less than 24 hours later, she called again saying the car was now delayed, they want to reschedule for Sunday 9/30. I told her I was out of town this weekend, could take delivery Friday otherwise it will have to wait until next week. She wanted to schedule for Friday and "if it's delayed we'll just move it again." I put my foot down and explained that I'm taking time off work, moving meetings, etc, and do not want to schedule another appointment unless she is sure the car will be there. So now we're back to the original delivery date of 10/1, with a different VIN.
I think this week is complete chaos and they're matching people up with cars at the last minute depending on who and what is available. I wouldn't trust any VIN numbers they send electronically until you actually have the car in hand.