I am planning to create a Windows Domain through a Windows Server 2016 or 2019, however the Windows server will be installed as a virtual machine in Hyper-V. Since Hyper-V requires selecting membership of a Workgroup or a Domain, right after the setup, what steps should I follow as the Domain will exist only after installing the Windows server. Therefore, should I initially join Hyper-V to a fake workgroup and then, once the domain creation has completed, join the Domain?
Microsoft recommends joining the Hyper-V host to a domain. You certainly can join it to the domain of the guest DC.
Hyper-V itself does not need the DC for any Hyper-V related functions. Hyper-V will happily run and start any and all VM's without having access to the DC, so there is no chicken or egg scenario.
The domain join process is completed before the computer joining the domain reboots. The domain join process does not complete during the reboot. When you reboot the server, the server itself is reconfigured for domain membership. It does not at that point need any connectivity to the domain, so, again, there is no chicken or egg scenario.
When the server reboots, you can simply log on with the local Administrator user account. If you want to cache the domain user account credentials on the Hyper-V host then simply log onto it remotely (RDP) with your domain credentials after the host and guest are up and running. Once the domain credentials are cached you can log onto the server locally with those credentials... whether the DC is running or not.