OK so topping, what i just saw in a video is cloning. Topping is much much much less.
Take the head, where all the new growth is , spread the thing, its two tiny leafs covering hairs . Cut the hairs 60% off or more for topping, less for fim.
The white line, is too much and removes your leafs which will supercharge the topping growth below. See pic one.
Pic 2. I hacked off too much Both leafs, AND the hairs.
Pic 3 shows some good topps , and one where i cut the leafs ,
Less is more. Unless you want clones.
Worth noting the smaller bits of hairs failed to top. The two extremes are bad, right in the middle is a nice functional top with leaving the leafs.