Hey!
Stress in general can cause plants to herm but mainly light and heat stress are the most common factors for plants to herm.
It can happen at anytime of the grow cycle but mainly happens during flower.
If you start seeing what looks like tiny bananas on the buds, she's hermied on you.
I had two herm on the last 3 weeks of flower, one only had 4-5 seeds out of 70G of bud. The other one only had about 3, I got REALLY lucky.
Normally when they herm early on you'll have more seeds than buds.
Good luck and Happy Growing!😃🌱🌿🌲