topping from regular seed?

So I was asking from some help in the seed and strain review section about what kinda seeds to order and someone said

"If you top your plants from regular seed you can get the clone sexed before you put the mother into flower. Takes a lot of work out of growing male plants into flower. Not as easy as Feminized seeds but it's a mid step."

I was wondering how this process was done. Also if anyone is experienced with FEM SEEDS I was wondering how likely they were to go hermie and if there's a partiular kind (ie Genetics) thats likely to go hermie vs others that won't...

i wouldnt use the top myself, but you cut a branch and put it in a cup of water on 12/12 lightingand it will start showing sex in 2-4 weeks(maybe sooner possibley)