I ream after it is turned.
The Latta method is by far the best one for longevity of the call for the end user.
If you want to make it easier on yourself, get a 43/64 drill bit and a 43/64 mandrel (custom by Flint Hills). That way, you don't have to turn the guts down so far for the Latta method.
That little bit of material makes a huge difference, especially for the bit reed calls since they have a sensitive (thin) neck.
Vince