I want to use this recipe for cupcakes. Can you tell me if the time should be increased or decreased?

Ditto to what Nancy said! The cupcakes will bake for less time—I would start checking in around 12 to 15 minutes, and go from there.

Most cupcake or muffin recipes bake through in about 15-18 minutes in a moderate oven (350-375F or 160-180C).
Maybe check on them starting about 12-minute mark and rotate pans (front to back, up and down) if you see uneven baking.
Cupcakes are done when the usual toothpick or wire tester comes out clean from poking in the middle of one.