Wear protective goggles and measure the location where you will drill the hole using your tub fixture template. Place several layers of masking tape around the location and mark the location with a black marker. The masking tape helps protect the surrounding tub areas from chipping as a result of the drilling.
Place the 1/8-inch drill bit into the chuck of the drill. Drill the hole, but don't use any force--let the drill do the work.
Remove the 1/8-inch drill bit and insert the hole saw into the drill. The hole saw should be the same size as specified in your tub fixture template.
Drill the hole with the hole saw. Push the drill forward slowly and evenly until you have reached the length you need. Vacuum any debris with a vacuum and hose attachment.