Usually around 3 or 4 weeks from sprout , you don't want to top too early but you can always stay longer in veg and top multiple times... check out this technique called fluxing, combining multiple toppings and training over just 5/6 weeks from sprout !
Hey I hear people do it after 5 true leaves but I do it as soon as I think the plant can take it. I mostly have done this with the photoperiod strains and I asked the same question about autoflowers yesterday as it's a slightly different scenario . 👍
Hello ! The best time is after the 5th node and before the 7th node ( to me ) and for a scrog you should top before the plants reach the net to build a flat cannopy. I hope it will help you 😁👍