Custom order will typically cost more as there is no inventory the dealer is sitting on. I would expect a 20-30% reduction from MSRP once we are in 2021. You can find that now with 17/18 cars. My car is a late 18 build, for other manufacturers it would have been considered a 19, but there were officially no 2019 Evoras imported to the states. If you have to have the 2020 though, it's going to cost you... therefore a 2018 strategy is worth considering unless you are dead set on the new bumper, etc.
Also if you order custom, here is something I would not pay extra for: Premium sound. I just redid the system this weekend, the speakers have such small magnets they won't even stick to a piece of sheet metal, they are crazy bad. It's a close second for worst audio system I have upgraded in modern times, the first being the base system in a Chevy Colorado.
I would also avoid the 2 seater only option. You can install/uninstall the 2+2 rear seats, without tools, in 15 seconds.
Happy hunting!