Hello Dr.Nadeem,
The basic advice I can provide is to possibly wait until you have a decent amount of time, as that is great storage upgrade (assuming you have decent amount of data and the most current software and version upgrade enabled with your iCloud Plan. I doubt the newest update 17.6 (and if you are not in specific developer preview OS programs, as to have automatic installments etc that would interfere with the timing of your iPhone Content Transferring).
If MDM work plans are not in your Apple and or other Professional Services /Business Plan on account, I would recommend doing over night, keeping connected to power and locked and going through settings to set as you’d like and verify Find My is not enabled.
Hope all goes well and Apple Support App has on demand call back services, as well as support coverage that should get full account access and all of your important data etc.
I am having a similar issue with IP network server and my HotSpot acccount and new conditions to network work changes were a concern with compromised data loss with manually transferring accounts and devices.
ill check back in with advice for myself as well~ good luck
katiefoos~iCloud