Not sure of this helps you. Here is my situation.
I ordered at the beginning of the month.
Set trade in for mid Sept. Then requested delivery in mid December. Was informed this was only possible with a custom order.
About sept 10th was informed that they are not supposed to delay delivery any more. The contact at tesla, was not aware of this when he said it was possible. He would make it work, at least one last time. Good reason to have things in email.
They picked up my trade in, then a few days ago they had to reorder the car, because they could not change the delivery for mid Dec.
He said it was common to do a reorder.
Although my situation might be out of the ordinary to have the trade in so much in advance of the delivery.
Just sounds like the days or custom delivery dates are the thing of the past.
No surprise seeing how they will hopfully soon double the amount of deliveries.