They look very good dude. Shit man, better than my current clones.
They do look a little early to top. I do NOT think they need more nutes, that much I am positive about. The color looks fantastic so don't fuck with them. If they are growing slowly then hit them with more light or increase temps. Fine to go low 80's during veg, especially if you have co2. Just keep the nights warm as well.
In terms of topping, I wait until I see a good set of 4 branches that I want to become the four main branches of my scrog. Then cut pretty much everything off below those 4 and clip the top. As those 4 shoots grow, bend the tallest one down to keep them all growing evenly. I don't know what your finish height is but, on those four branches, I am clipping off the new shoots for the first couple-three weeks.
Basically I am growing a plant with four big branches and keep them pretty bare except the growing shoot. This will make those branches THICK. Now, when I have about 3 weeks till I flip them, I don't trim anymore and the new branches grow out of the main stalks quite quickly. Under the screen, each of those four branches is trained to the corner of the scrog screen and the new shoots full in the inside and edge portions of the screen.
Your basically growing a lollipoped tree. I read about this scrog training method in the west coast masters book. It was very methodical (the rest of the book was utter newb info
). I can say this, the lack of having those long skinny branches that start at the base of your plant and struggle to get to the screen really makes a difference in bud size. My last round I had two grand daddy purps which are well known to have fairly average yields. I vegged for about 7 weeks in hydro and trained them perfectly. I just dried all my harvest and I got 2.20 lbs off of those two plants that each had a 600 under them. Zero popcorn. None. Zilch. Everything that came off the plant was good enough to be included in the grade A bags. Now THAT is a good feeling.
Good luck dude. Seems to me your doing fine