topping? pre veg light question!

Topping the plant is to increase the number of colas. It isn't necessary at all. It is just something that could potentially increase yield depending on the way you are growing.

As far as light on germinating seeds it's not important for them to have light until the have popped up above the soil. You could probably wait about three days before turning the lights on. As far as the cycle just do a 18/6 like you would during veg and they will be fine. Just make sure you have the lights set up as soon as the plants pop up or else they might stretch and be a little messed up.