I don't remember the signed agreement being uploaded into my account, however, I do know that the pre-transfer approval was processed when the $250 referral bonus was removed and I had to make an additional ACH payment to cover it. The MVPA for the MY will show Pay-as-you-go at delivery, and for 12 to 72 hours afterwards until they add your free supercharging to the car, at which point it will say Free Supercharging.
So I would say that the removal of your referral bonus is the signal that you're good to take delivery, since everything is put in motion in the background to make the transfer happen.