When to fruit?

It really depends how tall and/or wide you want them to be during flower. Typically, a plant will about double in height during the first few weeks of flower, as well as grow more side growth. Good luck

Probably two weeks usually need about 8 weeks to be sextualy mature I wait untill I see pre flowers

Hi, You are right, give them a couple more weeks. As for defoliation, if it were me I would remove the inward facing shade leaves and keep the outward facing leaves like a fan of solar panels. Usually every node at this stage has one leaf that faces more inwards than the leaf on the opposite side of the same node. This makes it quite easy. GrowingGrannie posted a link to a decent write up on defoliation. She is lovely despite what the trolls may have you believe and im sure she would have that link on hand being the resourceful giver she is so I would recommend DM'ing GrowingGrannie for that as its takes the time to explain the fundamentals. I hope that helps Sticky Buds!

If you question is about defoliation, I'll suggest you read this article which has become my "bible" as far as that topic is concerned... it explains the when, the why, the how - and gives good solid reasons for each and I think you'll find it answers all your questions and more... https://www.growweedeasy.com/nebulas-super-simple-3-step-defoliation-tutorial Good luck!