Several questions.
Would it make sense to turn off the old hub and update the new one first?
I am a HubProtect subscriber and I just made a cloud backup as a test run but under Migration Ready Backups nothing appears. The Docs said to be sure you saw a backup there. Am I missing a step somehow? I don't see anything extra when making the backup.
On the list of all backups there are check marks for Zigbee and Z-Wave so I probably am good?
C8 might not be seeing the cloud updates due to the initial launch platform issues. I would definitely update before migrating.
You also wont see the backups under migration ready on the C7 I don't think, you can only "migrate" to a newer hub model.
You can keep the C7 running if you want for the getting the C8 updated part.
You could either boot the C8 up and set it up as a new hub then update form the normal UI, or what might be easier is to just use the diagnostic toll and "Download Latest" button to get it update. The install update from "Restore previous..." (works for updates also).
Once it is updated you can do a soft reset and reboot, then follow the migration process. Or if you are already in the main UI I think you can start the migration from the backups section in there.
Once migrated you can transfer your subscription to the new hub from the subscriptions portal.
Have company coming off and on thru the holidays so I may wait and make it an early new year project but thanks for the feedback!
When the lights go out during the holiday dinner just tell them that candles are more festive.
Finally getting around to this. Hooked up the C8 and connected it to ethernet went to 8081 and chose Download Latest Version and got a"Could not fetch latest version information. Figured I'd try again but when I closed that I have spinning green dots on the page. Sitting tight to see if it does something. It did update the hub date and time so it's talking to something. Suggestions?
Also figured rather than start from the diagnostics page I'd just do a normal setup. Got to the update hub firmware and I get update failed please continue. Went on in and everything seems okay on the network part but when I tell it to check for update it seems to get stuck on checking for update. It's been on that screen for well over a minute.
The C8 is currently on 2.3.4.148 if that matters.
Rebooted and now it's finding the update.
Well that was pleasantly painless. Thanks to all of you who migrated early and worked out most of the issues! 
Even changing zigbee from channel 20 to 25 found everything in about 2 minutes.
Download the Hubitat app
