I just made my payment online through Tesla prior to the delivery so it showed a balance due of Zero. On delivery day it took me like 5 minutes to sign a few papers and was so much easier than any dealership car purchase I have ever made. I financed through Tesla, because I got a good interest rate and wasn't worth the hassle of re-applying and jumping through hoops to save 7 dollars per month.
I was very pro-active however, and did not let anyone slack when it came to my delivery. I sort of bugged them to ensure everything was all set to go for delivery but maybe i'm a bit different than most.