I agree with earlier suggestions and free hand and use my Dremel tool with the 2′ extention wand, so I don’t have to worry about shocking myself. For me, it’s easier than a drill press because I can do this in the laundry sink in my studio, where water is easy to obtain. Also I order diamond bits which are hollow core and make a hole much faster. When I’m drilling thick glass, I will bring the bit in and out of the hole I’m creating to allow fresh/cool water at the point where the bit meets the glass.
Windows listen attentively for the sound of broken glass.