Note in your second picture that the largest leaves have just recently reached the outside lip of the pot. As roots generally grow out at about the same speed as the larger leaves you can figure that the roots are just filling the pot. That means the plant is still vegging and you have to make a decision as to what kind of plant you want - taller or bushier. Your plants are just reaching the stage where you can expect to see an inch a day in growth. If you flower now the plants will double in height during flowering (called "stretching"). I would leave them vegging another 2 weeks to take advantage of the growth spurt. Reason is that longer veg will force the plant to do more growing sideways (bushier) and you will encourage more growing points (aka bud sites). Also, continued vegging will result in less stretching and you won't have to worry about growing into the light. Remember, going to 12/12 when the plant is in full veg mode makes for taller (usually scrawnier) plants. I would rather have a bushy 5-footer than a scrawny 6-footer.
Works for me, BigSteve.