I was always taught to install screen protectors with the phone turned off. As you can see from my photo below, it was a big failure. If your screen protector is anything like mine it is cut to the exact layout of the screen, making the notch especially difficult. Because my screen was powered off, I didn’t mind the notch up with the glass correctly. It looks terrible because it’s not precisely right! Don’t be a dummy like me. Install with your screen powered on!