Well, you can only sex a plant after running 12/12 lights for about 7-10 days.
Then you can throw the males out, and generally once that big, I would just continue the rest into flowering.
I don't know how long they've been back vegging (18/6 or so) but if its only been a day or two, I would cut the the tops till you have the size you want flower them, and take the tops.... and again depending on their size, I would root them and turn them into clones.

keylime