I have perform some test with relatively small tables and the encryption took a very long time (maybe because there are many SQL objects that are referring the target table).
I am wondering(worrying) when a table is being encrypted, is it possible to read the encrypted data or query the table? I only found this:
While the data is being re-encrypted, your applications cannot write to the impacted tables. Therefore, your organization needs to plan a column encryption key rotation very carefully.
and it is about the rotation.