sounds nice man.
i would say that you can start LSTing as soon as your plant starts getting higher than you want it to... mine is just sprouting its fourth node at about 3/12" and i wont let it get any higher than 6"..
in order to keep it down (and promote leaf growth), im just going to place my pot in a stationary place, and bend the plant to one direction by the top, and tie it down to screen. Then, as the plant grows, you keep it growing horizontally by letting grow sideways in one direction. Just keep tying it to the screen.
peace