I use it prior to my carnuba topper so I use a finishing pad. (DACP + VM + #3 + P21s)
But if your finish is near flawless and you are using it as your first product in your routine, I would use a polishing pad to to fill any very minor swirls or slight, slight hairline scratches.
I have always used the #3 Machine Glaze with a Meguiar's Finishing Pad (w-9006) . In MHO, I am not using the #3 to do anything but put a glaze on the paint. Therefore, I want to use a pad that has very little bite to it.