Thee is lots of info on this site about this, but I remember my issues when I started. If you don't know the sex and want to clone for your next run flip the first batch and as soon as the females show take your clones then just let the other do their job. But most of the time the mother has to be about 4-5 weeks old min. in my opinion. If you have fem. s33ds then you can clone just keep track. In my experience, if you try to force sex then reveg you stretch the plant and stunt it overall. There's a little personal experience behind this. Good Luck, And Have Fun!