Hey Doc, Your well on your way. Don't sweat the three leave deal, you will notice that all your flowers will have 3 pronged leaves. I definitely think that the HID as soon as possible is a good idea. Anytime you change the enviroment though such as one type of light to another, transplanting, etc. I like to use Thrive Alive with vitamin B1. Really helps the girls through stress. The sooner the better on the HPS. As far as when to start flowering, each strain is different as to its veg heighth to flower heighth ratio. Most start there plants on the 12/12 when veg has reached 6 to 18 inches. I ussually shoot right down the middle at 12 and end up with plants 2 1/2 to 3 ft tall. Short plants use light more efficiently. I also like to trim the bottom third of the plants nodes to force growth toward the top where the light is. With good light you can generally get 1 1/2 oz easy.