In all gardens I've worked in and own we top the plants far later in veg. I would let it keep growing healthy n strong then when you notice branches that are excelling above the others you take their heads off to make them equal.
We let the plant grow until it has at least 12 node sets before topping, some of those branches end up as clones or just don't make the cut and end up being lollipopped off. Every run is different.
Do not start training a plant too early into veg, if its still in a solo cup its too early to train. Think about training a plant when its at least 12 inches or a foot tall at the earliest.