That depends on how and where you grow it. Generally for inside/tent grows, I like to top/FIM when the new plants are about 5-8 nodes tall. Topping will produce a twin branching ffrom the top off the plant if it is done before the plant reaches sexual maturity. Past that point the branches are alternating and will not normally develop twin branches.
I also like to wait until I have 7-9 nodes on sexually mature plants then do a FIM on them to cause the plants to form a bushy growth. Then if they are beginning to get tall again and not bushy enough, I will do a FIM on all of the highest tops.
I don't do any topping or FIM when the plants are already in flower, and If I do a FIM close to going to flower, I will wait at least a few days before placing the plants into flower after the procedure to allow them to recover some as it is a higher stress to the plants once in fflower.
I like fimming better than topping. It takes less of the plant off and usually gives you 4 tops instead of 2.
I would really recommend getting some experience before you tried any high stress training like super cropping. I personally prefer lst and scrog to super cropping--you get basically the same results without the high stress.