Hi there.. it's an autoflower which means that after around 4 or so weeks it will automatically start flowering, even when you don't switch to a 12/12 light cycle. That's perfectly normal, and expected behavior, because this is why the traits of the ruderalis strain was breeded in.
There is no "fixing" this, as there's nothing wrong.
Even with photoperiodic strains, the preflowering would probably appear around this time, which show you the sex of the plant, as it matures, but then you'd just not flip it to 12/12 for keeping it in the veg phase. Autoflowers (as the name implies) start flowering automatically, even without the flip of the light.
Best advice now: Keep on growing, get ready for the early-bloom stretch and once that stretch is over, switch to bloom nutes (don't switch now, else she might not get sufficient nitrogen for the bloom stretch).
happy growing!