Rebuilding large columnstore indexed tables - am I doing it right?
What I plan to do: •drop the columnstore index, create row-store index
  (this is to align the data in logtime) •then drop the row store index,
  convert the table into column store index (better compression and
  queries later)


You can use CREATE CLUSTERED INDEX...WITH (DROP_EXISTING=ON) to change the existing columnstore clustered index to a b-tree and then CREATE CLUSTERED COLUMNSTORE INDEX...WITH (DROP_EXISTING=ON) to change back to columnstore. This will eliminate the drop index step that changes the columnstore to a heap.

I still expect this will take quite some time with 60 billions rows. Although source data might not have been loaded in C6 order, data overall are typically loaded in roughly chronological order so there will still be a temporal relationship for data in the same proximity. I suggest you review the min and max values in sys.column_store_segments to see if this effort is justified, considering that segment elimination is done after partition elimination. The performance benefit might not be a great as you think.