Ideal install temperature is 75-85 degrees. If it is warm, do the install in the shade. Vice versa if it is cooler. Clean the surface of the light cover. Spray the surface again with StickerFab application fluid and do the same to the overlay as you peel it off the backing paper. This fluid will let you align the material perfectly and prevent it from sticking to itself. Once you get a proper alignment, you can push out the fluid and bubbles with your fingers.
Use a small amount of heat and your fingers to massage all the fluid out. Go slow and pull up the material to lay it down and re-stretch it when needed.