You are right and it depends on the gelatin and how well it sets up. Personally, I have found it works best before the chill set. I add as you said earlier, at the start of the heat set. I use dry gel to avoid further dilution. I also gave the amount of gelatin that I added.
The strategy is this: Low gelatin promotes formation of large grains for speed. Adding gelatin protects during further heating and I have found that it helps to be there during digestion.