...should I only pay once the VIN and the MVPA appear in my account?...
Yes.
...will I not get those either until I pay?
Yes, you will get those before you pay.
Before you pay, you'll get:
1) "Motor Vehicle Purchase Agreement Vehicle Configuration"
With all the prices listed including the destination charges but without the rest of other fees, taxes, titling, and registration just yet.
When your car is ready for delivery, you'll get another one titled:
2) "Motor Vehicle Purchase Agreement Final Price Sheet"
This one is almost exactly like the one above but now with all the rest of other fees, taxes, titling, and registration.
Notice that both above documents would have your VIN.
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I was answering for those who are anxious to pay, then look for the available option to input for payment on your Account page.
If it's there, you can go ahead and enter your bank route and account.
By that time, you should have the document #1 already so you would know the approximate amount excluding future calculated taxes and other fees.
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Texas does not allow Tesla to sell its cars instate but it does not forbid you to buy Tesla outside of Texas.
You can either physically drive out of Texas and make payment outside of Texas and drive your new car back to Texas or
You can also pay Tesla Head Quarter in California which is outside of Texas as well.
That's why you just can't bring a check to pay Tesla at a Texas locality on the delivery day.
The handing over of the money must be arranged outside of Texas in order to comply with Texas laws.