"Punching the trigger" is the biggest shooting problem among bowhunters today. The very best way to avoid this problem and shoot well consistently is to use a surprise release.
The index-finger release facilitates punching. That is, it makes it easy. That's because the index finger is very easily controlled. It has great dexterity and can work with lightning speed.
If you have a problem with punching the trigger, use a different style release aid altogether. Try a thumb-style release aid or, better yet, use a back-tension style release aid, which all but guarantees a surprise release.
If you insist on using an index-finger release, there are several things you can do that might help. First, try gripping the release aid deeper — up to the second joint of your index finger. Don't pull with the index finger, but rather use the large muscles of your back to trigger the release. If that doesn't work for you, try using a spring as a trigger instead of a solid post. The spring bends farther and farther as you pull with your finger until the release fires.
Remember, you can always get on the trigger quickly if you must in a hunting situation, but during practice, always use a surprise release.