Be truthful and ask. I have had dealers on several occasions delay delivery until January 2, so I wouldn’t need to pay that year’s property tax on the car. One just had the sales order with my signature and let me test drive for a couple of weeks before finalizing. The other made up two sets of papers, one with the current sale dat, and the other with January 2 on it. If I didn’t come back, had an accident, or some other unforeseen occurrence, they had my legal signature. Tesla is different in that they don’t care, and they are highly automated. Ask them if they can arrange something if the car actually does come in before July 1. You probably won’t be the first to ask. It may be worth to reject the car if no other options. That is a bunch of money. You will be waiting a long time if you reject, or you will be paying more than $4000 over your current deal anyway.