Custom Domain - Verifying production domain in dev tenant

I have separate tenants for DEV and PROD. They are both currently using the default domain provided by auth0. I’m planning to give each of them their own custom domain: and

To save some time during production deployment, I am considering setting up the DEV tenant ahead of time to initially use the PROD custom domain so I can have the networking tech setup the DNS, do an initial verification, and test the url. Once that’s successful, I would change the DEV tenant to use the DEV custom domain and repeat the steps. Then on production deployment day I’ll know the custom domain dns is already setup. Is this plan sound?

From what I’ve read so far in these posts is there could be a delay between when I enable the feature and the verification of the dns entry. Would new users be unable to login to the app while the verification process is occurring? Would currently logged in users be unable to continue working in the app?