i like to allow my plants to reach sexual maturity before i flower her.. you can tell this by one of two things.. either when she starts putting out uneven nodes or when you start to see preflowers..
you can flower before this, but to me its like the difference between a 13 year old girl having your baby or a twenty something year old.. the 13 year old can have a baby perfectly fine, but the baby is gonna go through some stress and probably not gonna end up as good as it would have if the 13 year old would have waited till she at least finished high school or even college and has a good job and etc.. just the way it was explained to me and it made good sense..