Switching to CloudKit

[cgrunenberg]

See e.g.

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

I’d like to migrate from iCloud Legacy to CloudKit. I have 15+ gig of data over 6 databases. Some a lot smaller than others. I have two Macs (desktop/laptop) and an iPhone. Should I sync with both Legacy and CloudKit on ones of my Macs, turn off legacy on my other devices, then enable and sync CloudKit?