What is the best way to migrate from iCloud (Legacy) to iCloud (CloudKit)

This is very helpful—thanks! On the same theme:

  1. I’ve added DTTG 3—for now, what are the pros/cons of uninstalling DTTG 2?
  2. If we don’t uninstall it now, should we also turn off the Legacy iCloud on DTTG 2?

Appreciate the help, as always!