I, too, wait for decals until everything else is done.
I apply them wet--using a spray bottle of water with a couple drops of dish detergent. Wet the hood and the back of the decal. When you apply, the decal can slide a bit to get it perfectly aligned, and then squeegee out the water with a soft rubber squeegee to adhere the decal to the hood. Let dry overnight.
You can apply them dry by taping them in place with blue painter's tape, lifting the decal up on the "hinge" of tape, remove the backing and smooth out. It's tough to do this without getting small air bubbles under the decal, so that's why I use the wet method.
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