Plant not flowering

[Sambus420]

Hey guys, am having a little problem with my other plant, im 20 days into flowering yet my other plant isn't showing any signs of it. last nite i put it in dark for 12 hours and it perked up but today its back to way it was before that. also the plant is like half the size of the other one .both should be autoflowers and light schedule is 18/6.

pics https://imgur.com/a/70r9Ifq

[9fingerleafs]

Maybe that one is not auto.

[Sambus420]

what should I do then if that's the case? can I just switch the lights to 12/12 or would it affect the other plant? thanks

edit: my first time growing btw

[Weed Pharma]

I would keep the 18/6 light schedule.

[Ace3785]

It sounds like a photo to me also. It will affect the growth of the other plant a bit. Unless you use her for clones, then you can keep her on the same light schedule. If space really isn't a bad issue, keep veging her until the auto is finished.