for topping you do want to wait until 5 nodes are evident, your VPD wasnt optimal so topping this short plant now will stunt it forever, if you want to train it and keep it in veg, what you do is you prune any leafs that gets 5 leaf tips - this will keep your plant in veg for up to 8 weeks, and therefore you can train it anywhich way you want to . Hope this helps ! 🚀