They are too small and go to flowering mode, am i ...

@Saber hi mate they are autoflowering seeds so they will go to flower regardless of size What you should now do is focus on a feeding regime suited for blooming ie P+K Happy Growing

Like the others said. Feed her with bloom nutes and get some bud! Have you given any nutrients yet? Next time focus on 2/4 plants in much bigger pots. They will be bigger especially under only 400w

The size and health of the plants will never dictate your question. You have to consider the nutrients accordingly to the stage of growth they are in. Now your pistils are out which means the plant wants to produce her fruits so she will need more Phosphorous and Potassium and less Nitrogen. Only thing you can control now is the flower development. Super Lemon is a fantastic strain btw, you'll love it if you give it a proper cure you'll taste and smell the limonene terpenes ;)

Hey there Saber, sorry to say, but there's not much you can do by now, that's just the honest truth, the best thing would be to switch to flower nutes and get those temperatures as low as possible to make sure you get at least some decent top shelf bud. That's just about all you can do right now, hope this helps 🚀

Usually with nutes they have a week by week feed schedule with a transition feeding between veg and flower. Not sure what nutes your using but you can check there website out they should have a feed chart there hope this help!

I start the bloom food when I see the first preflowers. These being autos they will finish on a time table, cannot use lights to prolong the veg cycle. They will not grow into monsters as the small pots they started in probably got them a little root bound.