if you are bending because of space, topping will only make the plant use more space. Depends on how you want to bend, if you want something like Harddons, I would not top unless you got the room if at all, if you are bending in the shape of Zoro you can top and I would do it before or right when you start topping. If the plant is 2 or 3 weeks old, bend the plant slowly each day a little more till the plant adjusts.