Can I/Should I TOP or FIM these plants?

hi guys I have been doing a fair bit of reading on 'Topping' and 'FIMing' a plant, being my second grow i want to give it a shot as I see it's the way to go. I have 3 plants out of my 7 I would like to top. Here's a couple things which is holding me back and a couple questions I'd love you guys to answer for me.
-Do they look old enough to TOP or FIM?
-Should I TOP them or FIM them, what would you do?
-Plant 3 the plant looks like it's already flowering. Should I keep this plant even though it's small and flowering?
-I know not to TOP or FIM in flowering but would it be to late for plant 3?

Plant 1.


Kera Critical (Plant 2).


Plant 3.



Really not sure what I should do :/!

Yea top em after 4-5 nodes but id mainline em they look like good candidates

Thank you Gunnar&Carey, much appreciated!

you can top or fim
quite soon as 3-4 nodes and supercropping i normally do 2 -3 weeks veg but i noticed less is more mate the more you top and fim and super crop doesnt always result in better harvest i would say one or the other

I figure a plant is big enough to top/FIM when it has an identifiable crown. The plant in pic #2 just meets that standard and is ready to cut.

Topping should lead to 2 main colas while FIM'ing usually results in 3 or 4 main colas. FIM'ing has less effect on the rest of the plant than does topping. So, I would top those plants that look thin or scrawny. Topping them will help them fill out some of the empty spaces. FIM the others to increase bud sites.

Good luck, BigSteve.

i would top them, i top all my girls 5-7 days after i transplant from cubes to coco/soil. They are usually about 6" tall when i do it. Then i top one or two more times depending on the strain. usually i veg for 3-4 weeks.