First grow update! Root question as well

[TwoManyThumbs]

Man its been awesome watching these little bbies grow . Theyre starting to get all bushy ( can barely see the stem !) So I want to throw them into flower soon, BUT I feel they have weak roots still. When I first got them as little ones, they started to go into flower. With 18/6 light they came back around into veg, but i feel they never really developed a good root system. So my question(s) is/are how can you check your root mass without stressing the plant? should I just throw a little root bloom in my next watering then wait maybe 2 water cycles and throw them in flower? They are a little wobbly when i push on the and I can see the soil moving by the stock, kinda like its not fully rooted, or is that normal?
Overall im loving it. I have a light gnat problem too so im drying out the soil and spraying soap water on them when the lights go out. I plan on getting some neem oil as well. Theres a few thing I need to get and take care of before I jump into flower. The roots was one of the main ones.
My plants are a little saggy in the bottom pic cuz theyre getting ready for sleep
As always, any info is greatly appreciated.
First DAY:

NOW:

 

[Aegupton]

plants look healthy.so these spots on the leafs are from gnats ?

 

[AKgramma]

If you want a good yield, you want to let your babies grow into juveniles. I would train them using any method you wish to get more branches, and not switch them till they are 3 months old. You can tell they are mature when their leaves start growing in an alternate pattern instead of across from each other on the stems.

 

[Croatsan]

how can you check your root mass without stressing the plant? should I just throw a little root bloom in my next watering then wait maybe 2 water cycles and throw them in flower? They are a little wobbly when i push on the and I can see the soil moving by the stock, kinda like its not fully rooted, or is that normal?

Hi TwoManyThumbs

I would use some kind of a root stimulator for, at least, couple of weeks and then flower them. They sure look healthy.

All the best.