Because I couldn't find any description from Esri about this situation I decided to follow the flow for other servers:
In short:
1) Install all NotebookServer and docker stuff on the new machine
2) Move Config from old machine to a shared location that is available for both machines
3) Join Site with new server
4) Test en docker save&load custom docker images to new server
5) Edit federation details such as admin url to new server
6) Disable old server
7) Move config to the new server and clear shared location
Just arrived in the testing phase bus seems to be working
