I wouldn't top or FIM and auto it stresses the plant out resulting in less dense buds. Also, most Auto-flowering strains start automatically making buds (flowering) when they're 3-4 weeks old. Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.
Don't top an auto it's too much stress on her bro, LST Is fine not HST on autos, shouldnt be long before seeing preflowers if it's good genetic auto, happy growing