Ha. A little birdie (not you) told me exactly this as well. Very possible to get a GS first (perhaps with no more power and just aero/handling) and then Z06 later. So it could be north of two years for a Z06. I have a deposit on a C8 Z06 but if GM goes flat plane crank, I will cancel it and wait another year or so or just get a GS or Z51. Or GT500 or something else. There will likely be growing pains with an FPC higher displacement, higher horsepower engine and I don't wanna be the GM beta tester with a $100K+ car.I'm getting signals that GM may have changed the launch order from what they did in C7. For C7 it was Stingray then Z06 (widebody and SC) then Grand Sport (widebody), but now it's looking like C8 might be Stingray (2020) then Grand Sport (2021, widebody with eAWD!!) then Z06 (2022 widebody with 5.5L FPC).
The "very soon" would be Grand Sport in 3rd or 4th quarter of 2020.