Here is the video they sent out to dealers on:
1. How to enroll into this program.
2. How to file for the incentive (for each buyer)
They specifically say the dealer will have to pay out of pocket during the purchase agreement. Then file for the incentive and then they will repay the dealer. But they also show **in written form** that (24:55)"For Tesla vehicles and other vehicles ordered without standard purchase/lease agreements, the date of first registration is considered the date of purchase or lease"
This incentive is not built just for Teslas, they are for all EVs. Only Tesla has a "Order Date". Since this has to fit all dealership types, they require lease/purchase agreement date, which is the date you sign all your documents at delivery.
To see which documents the dealership has to upload look at 25:57 in the video. "Purchase/Lease agreement"
These people giving out incentives need the day you sign your papers, until then the car is not sold or leased. You can cancel the order like you did, they dont care for that date.
And just to make sure, I googled a picture of a Tesla purchase agreement and yep, no order date anywhere visible on paperwork. And paperwork is what you upload, not some online order dates.