This above.There is a standard position. The handlebars have hole drilled in them and the brake lever housing has a nub on the underside that fits in the hole. If you are gripping the brake lever with 4 fingers you shouldn't be rotating the throttle at all.
Use all four of your remaining appendages to cover and use the front brake lever. Don't keep your index finger wrapped around the grip and just use the remaining three if that's what you might be doing. We call that the "pacifier"... It gives you a tendency to turn the throttle while stopping. Using all four fingers on the brake will help you to not turn the throttle at the same time. It's good practice anyway. If you ever went down, you would probably lose that index finger.