Hey Fuzz build looks great. As Waz said get a flat piece of scrap wood, glue some 80 grit paper and get a right angle and rub the nut on that (that didn't sound flash did it). The right angle will keep the nut square to the sandpaper. Put a pencil mark on the nut to roughly how much depth you want it to drop and test string height regularly

That green bass is stuck on volume 10 !