Light switch for feminized and for regular seeds until hair shows. But it doesnt really matter in the end. You would need to see if buds are riped or not. But for reference purpose i use the above method.
why the difference between the 2?
makes no sense to me
you do it from when you switch to 12/12 thats when they began to flower
some people I noticed are running around here saying when you see the first pistils
but I belive that is totaly wrong.
The plants growth pattern and chemistry change as soon as you switch