Not really sure what that is specifying to be honest. It looks like 3rd quarter 2017 which it is. But not sure if the AD1 bit is specifying build, compliance or delivery. If there's features/options in the MY18 that you're going to be upset about missing out on then I'd request a MY18 car and see if they can swap it.

Obviously the dealer is going to be interested in moving this MY17 car ASAP and not losing money on the deal because of it. I'd go back to the dealer and get them to clarify what they meant by this and also that your "understanding" was that it would be a MY18 spec car given that it was ordered in June and they would not have been able to order a MY17 at that time anyway. If it was a factory order then you'd be looking at 3 months minimum.

It really looks like they've swung some cars around and got you a MY17 sooner. I'd call their BS with saying that MY18 will only be around in December as they'll have them rolling up in their showrooms very shortly.