I think turning handles could be broken down to 2 main processes, plus "other". do you:
1) drill the hole first, then mount the blank on the lathe from the hole. (hole facing left)
2) mount the blank undrilled and use the lathe to drill or bore the hole. (hole facing right)
3) something I haven't thought of.
I do the second one.
Not sure how much weight my vote should carry, having turned all of three handles (!) but I do the first one. Mostly because my spindle fits a 24mm hole perfectly, and the first two I made were for 24mm knots. So for those, I drilled the 24mm hole in the blank, mounted them in the lathe, and turned away. I have a couple of 30mm knots on their way soon, so for the handle I turned yesterday I drilled a 30mm hole to start with, and then drilled a 24mm hole inside that. And then mounted it. It seemed to work, but there is definitely some potential for shortfalls in terms of precision doing that. I'm looking forward to seeing how others do theirs.
My approach is also due to my having a very simple lathe with no extra toys at all (i.e. no chucks). So once I'm able to mount a drill chuck, I'll definitely give option 2 a shot.
all of the rounding the blank and all the boreing (doweling if multiple materials) is done on the southbend metal lathe.
All of the shaping is done on the rockwell wood lathe,some chucked,some between centers.
I generally rough the blank between centers, mount it to a glue block with hot glue, turn the handle, drill the hole with the lathe, finish the handle, cut and remount on a friction fitting and finish the bottom. I use that friction fitting throughout the finishing process if I finish with varnish.