hey mate, no if your just topping, select a node and top, you want to take the very top off then go to the node just down from it and cut across, its that simple, i was worried when i done it first to, taught it might kill or hurt the plant, but in fact it stimulates lower growth and makes it bushy...
i know its a hugh forum, i`m in the irish growers thread along with few good guys, if you like pop in there and you`ll get any answers you need and decent advice, hope this helps mate.