I've only had one plant outta dozens that Hermes from stress. I'm pretty rough with my plants too. Hard temp swings, cold nights...etc. Any way, a good guideline would be day 21 and 49, for full strip of basically anything you can get at without damaging the buds. All fans.
I second this. I’ve really only experienced herms from seeds that came from herms. I just spent an entire grow trying to stress my plants into herming, including turning my lights on during lights off, flashing different color and strength flashlights during lights off, and messing with their diets and environments. Still couldn’t get them to herm.
I’ve long suspected some “breeders” of using bad breeding practices and inferior plants to produce seeds then blaming the grower with fairy tales about their environment.