should i flower?

Alright, so today is day 39 (since the plants sprouted) of my first grow and they're all bagseeds so the strain is unknown... but they all have on average 9 blades per leaf, so i'm assuming they're all mostly sativa mixes. the one in the second picture is about 16" and i topped 3 weeks ago. as for the first picture, the one on the right I topped 3 days ago because it was getting a bit too tall and is 22". the one on the left is at about 20". I haven't seen any signs of preflowering, but i wanted to get these gals (hopefully) into the flowering cycle before they got too big.

I hear sativas can triple in size during their flowering so i wanted switch them before it got out of control. any ideas on whether or not i should change the light cycle? any tips on how to keep the height of the plant down. it's a little late to LST, but i'll probably try it next grow.

You can always bend her over a lil. I've read of people's plants getting to tall during flowering and they just slightly bend them 10 to 15 degree's

I am not sure about it being too late for LST. That or bending it below a screen is the only way you are going to keep the height down. LST or SCROG will give you an even canopy, and let you get everything closer to the light... rather than having a traditional Christmas tree shape. You just have to be careful about bending thick stems {or tender ones for that matter} too much at once.

People flower much smaller plants all the time. So its OK to go 12/12 ESPECIALLY if you don't plan on LST or SCROG.

The more heads a plant has, the slower it will grow (vertically). Your untopped plants will grow considerably taller than the topped one. When deciding on a goal for finished plant size, you consider the maximum distance away your flowering lights can support healthy plant growth. This minus the distance between the plants and the light is the tallest you want the plants to grow.

thanks for the info. has anybody had problems with their crop turning hermie from changing the lights too early? i know not all plants will do this, but if it's susceptible to stress then it will be more likely to turn hermie, but i'm just wondering if anyone has experienced it firsthand?

Think of 12/12 as more of a release for the plant. You've been holding it back from flowering all this time and it can now finally finish growing. If a plant is stressed after going into flowering, it would be from something like not enough nutes to support bud growth, the transplant or something other than the light cycle alone.

You only really "need" 3-4 nodes when you flower. Those plants are far beyond anything resembling flowering too early.

thanks mother's finest