Technically I don't think there really ever is a time that is too late for topping.
I just recently manifolded 2 plants that were on their 7th node. As you can see by the pictures they were lush and bushy and I was a monster to them chopping them down to their 3rd node and everything below except 2 main growths... but that's ok.
As long as your plants are mature enough to handle it (and yours are they are at least 6 nodes but I am blind and blurple makes me sick so I can't focus well on your pic) you can literally chop them in half and then some, and that's in fact a strategy that is employed.
The tradeoff is time, the more aggressively you top, or more tops you ... top, the longer it will take for the plant to recover and for it then regain all that lost growth. If you're worried about overgrowth in veg don't be, because you can be vicious and they will bounce right back as long as they are old enough +6 nodes i'd say, and only do this in veg.
I'm not saying to manifold like me, just using my current grow as an example that if you're worried your plants will overgrow your tent when you flower them you can top, train, manifold, etc. them down to whatever size you feel comfortable (I usually flip lights when they are half the height I have to spare).
I will try and show you pics in a few day's to show that it will almost look like nothing happened they fill in so fast.