Just my personal experience:
Several years ago, we ordered a brand new car. Sat down with the dealer and the options book. Delivery was expected within 3 months. It was almost 6! And the car was tough to get fixed because of the off-standard combinations of options.
Since then, I have always chosen a car that is on the lot (my new Jayco as well). It leaves me in a better position to negotiate price since the dealer is paying interest on the inventory. In 20 years and 8 new cars, I've had only 1 that was troublesome.
So, my opinion, is that one should try and find an RV on a dealer's lot that will fit your needs as it stands. With the possibility of minor changes to make it uniquely yours.
Remember that waiting will be part of the price you pay.
TT 2015 19RD "TheJayco"
TV 2003 F-350 "Montblanc" - Housebroken chore truck
Sitting in The Cheap Seats.
And proud of it!