I suggest patience. The first availability for anything seems at least a month away and appears to start with the Z7 and Z7 "kits", so the body with and without different combinations of the
Nikon FTZ Mount Adapter and Nikon NIKKOR Z 24-70mm f/4 S lens. The Z6, Nikon NIKKOR Z 35mm f/1.8 S and Nikon NIKKOR Z 50mm f/1.8 S are staged to follow in October and ... then additional lenses in 2019-2020. (Edit: The Z6 and Z6 kits are coming in late November.)
It has been suggested that the "S" suffix in these lenses indicates "Silver", as in "Silver Ring" lens. If that's true, then I don't see any Nikkor "Gold Ring" lenses in the announced lens roadmap; they are all "S" series lenses.
That combination of single memory card slot and all Silver Ring lenses may be Nikon's way of indicating that the "Z" series mirrorless is not intended as a "Professional" line? Perhaps there is more to follow?
While there is a lot to like about the Z mirrorless bodies, I do have 4 concerns:
1) Single memory card for both bodies. While I suppose that I could have understood a single card slot for the Z6, the decision to omit it from the Z7 seems off-putting and short-sighted.
2) Short battery life. 330 shots (CIPA) for the Z7. 330 shots is awfully paltry by today's standards. The Nikon D850 is rated at 1840 CIPA for still-image acquisition, for example.
3) Need to use the Nikon Mount Adapter FTZ for lens selection for now. The Nikon mirrorless lens roadmap is pretty limited to start, meaning that you will need to use Nikon "F-mount" lenses for many/most serious/professional applications at the start. While the viability of the lens adapter is not known, early reports of usability are pretty good.
4) No Patterned AF-Assist from flash. I have only seen one report on this but it seems that these Nikon mirrorless bodies are unable to use a flash's patterned AF-Assist light. Nikon appears to have chosen to use an on-camera assist light, which is better than nothing but not a professional substitute. I've had to shoot wedding receptions in both a bar area and an outdoor, night-time European tent setting. In both cases the on-flash AF-Assist light saved my butt in providing fast and accurate AF acquisition. This is something that only dSLRs currently provide (as far as I have been able to discern).