The gun vise - fire- adjust crosshairs is an interesting idea.
But be aware that the turret markings adjust the POI rather than the crosshairs as you might expect. So the turret marking will be backwards.
Before firing I would optically center the crosshairs and, if the objective lens is adjustable, remove the parallax using the A-Team procedure.
Also I would determine the optimum zeroing range using the program CHAIRGUN. For my rifle 410E and JSB 8.41gr the opimum zero is at 17 or 38 yards.
The precautions in properly mounting a scope is a whole separate subject.