highly recommend getting a wrench for centering brake calipers like this:
https://www.parktool.com/assets/img/repairhelp/dual_008.jpgyou probably need a thin wrench unless you have a lot of washers that space out the brake against the frame
it allows you to both get the fixing bolt tight with your allen key and get good centering at the same time
i only like to use the tiny centering screw for the finest of fine tuning because adjusting it too much messes up the geometry, at least on asymmetric dual pivot designs (not sure about the latest 105/ultegra/dura-ace)
