When is it best to perform topping? It's goin...

now i dont think its the npk it liked but the water you’ve given it. your pot looks too dry in the first pic and plant seems underwatered so saturate the pot with water when you water everytime and wait till it gets lighter but not completely dry before watering again. the reason i say its not the npk is because youve already added worm castings or humus to your soil which should be enough to feed a plant that size at this point. so they were not suffering from a deficiency imo but underwatering. as for topping you can do it whenever you like and 4th or 5th node is an appropriate time to top. after topping also strip the very first node from the bottom of the plant because as you may have already noticed that is never gonna catch up with the rest. so top the top and strip the bottom and because your space is limited i’d suggest leaving 2 most similar nodes on the plant and aiming for 4 main branches. this may be 3rd or 4th nodes, 2nd and 3rd whatever. they should be similar in size to give you the most even canopy overall. strip the rest. thats how i do it at least haha.