Couldn't you just change your current order from MYP to MYLR? That will push your EDD to early next year, and you'll get the price in effect when you originally ordered. Then round about December you could change the order back to MYP if that's what you really wanted. And thus you'd get the new tax credit...
I'm debating doing just that, as we're on track to get our new MYP in the next couple of weeks. I've got a M3 SR+ that will need to be sold after we get the Y, but would keep it if we push the order out. With apparently declining used Tesla values (gas crunch easing?), that complicates the savings calculation WRT shooting for the tax credit. Carvana is offering more than we paid for the 2019 M3, but that will probably not be the case in 6 months...
That and we'd like to have the use of the new MY for the rest of the year (need it for towing small boats/trailers, since we got rid of our old ICE SUV).
Decisions, decisions.