No need for all that. Just align it with the line of dirt left by the wipers at the bottom of the glass.
I was only 'sorta' kidding. Alignment of your wipers is NOT critical. As long as they are close to horizontal when turned off ... good enough.
I've repositioned wipers before just because I didn't like how they sat on the windshield when turned off or to give a little more range on the upsweep.