Flowering on 18/6?!

These are bubbas gift, feminised and grown from seed with mixture of coco coir and soil, (maybe wierd mix to advanced growers but im new to this and it works) , and just your average household water.

About 2 month in from seed one had started showing considerable difference over the space of a few days, as you can see in the picture, is this starting to flower? I've seen it's impossible to flower under 18/6 And they've never had more than 6 hours darkness, generally they've had quite a stress free life and been really healthy..
I've never gone through the flowering or pre flowering stage before so really curious, also the one showing signs is half the size as the other, if they were autoflower by mistake shouldn't they go around abouts the same time? Baring in mind it's the smallest showing these differences..
Any ideas? There has been no long nights since the start and if this was cause both should show the same as they've both been in same room with same light..

This is my second one showing normal vegetative state but alot more bigger..

Basically just want to know If this is it going into flower, just showing sex, and is completely normal?

* also haven't put into flowering as only have 1 spare room and set off a 6 set on hydroponic DWC ( GOING amazing) a Bit foolishly and have to wait for these to be big enough to flower, before i can change to 12/12 should only be a month at the very most, but these two have gone at a considerably slow pace so hopefully not too massive by finish.. Lol .... It's all trial and error with being my first one and I am prepared for any problems, using standard 600w bulb conv and ballast
Many thanks in advance

the one plant must be an auto to be flowering under 18/6.....which leaves you in a bit of a pickle as you will eventually have to reduce to 12/12 so the other plant flowers..... the auto would do much better leaving it on 18/6 but it will be okay on 12/12

ISK said:

the one plant must be an auto to be flowering under 18/6.....which leaves you in a bit of a pickle as you will eventually have to reduce to 12/12 so the other plant flowers..... the auto would do much better leaving it on 18/6 but it will be okay on 12/12

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OP, if it's an auto as ISK mentioned here (it sounds like it is), can you keep 18/6 going for a couple more weeks then let it finish outdoors? You'd want to wait as long as possible so the plant outdoors has as much available sunlight per day as possible. As soon as she went out, you could flip to 12/12 for the photo plants.

I've got a 6 set in the second week, I won't be switching to 12/12 for at least a month and a half, ( as only have 1 spare room) which should be enough time but is this definetly going into flower ? And thank you for your replies it's really appreciated!
Many thanks ben

Also if it does flower in the mean time, it means I get some early smoke while the others are vegatating, I'm just worried my other one that's the same age as this one that's vegitating is gonna hit the roof by the time my 6 are ready for 12/12.. lol