Hello from Oregon willythepic. How old are your plants? Mine are now 5 months old from seed. My preflower has been happening for 2wks. Some of mine are further along than others, one is not showing any stigmas (hair) yet and plant is very large, it's gonna happen. Start preparing a spot if they are in containers to get shelter just in case. Also, I myself will decrease the N when I water and with the one who's not showing hairs yet I am doing plain water only, just to make it feed more off it's own plant nutes it is healthy and green so I don't worry about it right now. It's worked for me Goodluck