Lots of good stuff here - too bad I am 2 years late on this one! I like to use Pre pitch and Post pitch for terms when it comes to time between pitches. Pre pitch is just a few seconds long. It is when you get the sign, focus and throw... all the other time is post pitch. It is post pitch that screws everything up! All that time makes guys crazy sometimes. They go to slow, they go to fast.. they self talk too negative, etc. For this particular case I would have your son count. Yes count. Granted when he is jacked up he will count faster, but that is ok. Have a routine for how many seconds you want between pitches and count - you will thus be on que for the most part. Also, there are studies that show if you count rhythmically you improve your timing (it's an internal thing with part of your brain). So it would be like this..." 1,2,3,4 - 1.. 1,2,3,4 -2 1,2,3,4 -3.. etc. in a cadence - a 4-count. Hope that makes sense.. shoot even 1 mississippi, 2 mississippi would work great for this! All his focus would go to the act of timing and away from the stressor in the first place.
For more on the mental game - check out my website
www.baseball-cap.netGood luck
Rick