When I top, I wait till there are three nodes and then take the growth off above the third. This will give me 6 main branches to work with.
If you prefer more main branches you can go more. The consensus is always how long your wanting to veg the plant before you flip to flower. How big to do want the plant to be? All this factors into the decision. At three nodes in, then top, I’m able to flower a nice even canopy starting week 4 of veg and the plant has 6 giant colas in the end.
I hope this helps.