Yep
I think there are 2 approaches to topping:
- one is to top early while the shoots are still small - that is, to pinch off the top sprout that would make the 5th tier of leaves as soon as it starts growing.
- Another is to let the plants grow up more nodes and then to cut them back to tier 4 or so.
Personally I prefer the first way, as there is less energy wasted on growth that will then be removed anyways.
So yes, for the first approach, now's the time
I don't know the strains you're growing, but it looks like the CC has more of a hang towards sativa than the others -- have you given thought to how you will handle possible differences in height between strains?