You seem to get the best release of growth hormone with a combination of the amino acids - arginine, lysine, glutamine, and ornithine. The best time to take these is at bedtime when your levels of growth hormone are naturally raised.
Here's his recommendation for stacking amino acids:
Beginners - For a moderate effect, try 2 grams arginine, 1 gram of lysine, 1 gram of glutamine, and 2 grams ornithine. Increase to the following . . .