Moving mailboxes is a daily task for Exchange Admins. The process is the same as Exchange 2013 or 2016.
To move a single user mailbox you can use the following command:
- New-MoveRequest -Identity edwardvbs -TargetDatabase Store1
To check the status of the mailbox move you can run the following command:
- Get-MoveRequest | Get-MoveRequestStatistics
As you can see this one completed quickly as it is only 52kb.
Hope it helps.