You need a figure 8 cord to set it on a timer. You can read up on the AG light cycles on their website, but i don't go with that...i have my own timer that goes by what time of day it is. The new deluxe ones have a 24/7 option, but mine didn't so i used the figure 8 cord. You can buy it at radioshack, but i happened to have one laying around from an old lap top charger.
I would go by # of nodes before you flower. I think 5-6 sets of nodes is a good time, but depending on how much light you have and how big the roots are, you may be able to wait longer. Flowering at 2 weeks would probably yield about 5 grams...but yield is really dependant on a lot of things. My advice would be to make a journal, post pics and get opinions. B/c everyone has their own methods. Also read up on it, all this stuff has been talked about over and over.