About May last year I decided to purchase. I was planning on a 2018 model, ordered for November 2017 delivery, but in January dealer (who has been great) called to say 2018 unlikely to be available before third quarter of 2018 and did I want to wait that long? No! So August was the soonest he could get me one. So my plan is to enjoy the 2017, place an order for a 2018 upgrade model for delivery in August 2019 which gives me time to decide if I want to keep my 2017 or, assuming I can test drive a 2018/2019 and read up on any problems, upgrade in 2019.
I put down $1,000 (last year other dealers were still asking up to $5,000 deposit).