I would confirm with Yamaha directly, versus the dealer.

Why would the warranty start before boat is delivered?

What brand/model of boat? What engines? Just curious?

I think his last question is "will Yamaha offer the YES contract promotional event starting this July?"

If so, the answer is that only the Yamaha promotional program folks know. And they aren't talking. They don't disclose the start of the program until the day that it happens. You can call Yamaha Customer Support and they can't, not won't, tell you. Because they don't know. They also won't know until it is officially launched. Same with the dealers.

If history is any indication of the past or predictor of the future then it is likely that Yamaha will offer another promo program beginning in mid-July or early August. Whether or not it will cover the model that the OP intends to buy is anyone's guess.

You can discuss with your dealer the possibility of him delaying the sale of the new boat to you in the event it were to arrive early, before the program starts. The sale can be placed on hold until such time as the program is launched. Upon delivery of the boat and motor the dealer will register the motor at that time and can apply for whatever promo YES contract it is that Yamaha is offering.

But all else remember, if there is a program going on at the time you take delivery of the new motor(s), and you don't get the promo YES contract, it is the dealers issue to solve. Not Yamaha's.

Dealer has to get that customer's signature. So realistically the boat will be delivered mid late August? Will there be boat building the week of the 4th?