Issues with autos. Advise?

I bought a pack of blue mystic auto’s from nirvana, There about 2-3 weeks old from seeds, and 3-4” tall. I was taking a close look at them today, and it looks like 2 of the 5 are already showing pre-flowers. It seems like they are way too small to start flowering. I don’t know if it’s the seeds/strain, or something I did wrong. I grew some northern light autos not too long ago they were 18-24” before they started flowering, and over 3 feet tall when they finished. I was using LED’s on the northern lights, and switched to 400 watt HID for this grows. (which was set at 200 watts the first two weeks, and turned up to 300 watts a few days ago) Can anyone give me any tips on maximizing yields at this point? Thanks!

all autos are different, even with in the same strain. I grew some supercheese fems I made my self. most are stable but there are a few that are short/tall. I grew one that was 8" finished and the same strain one was almost 3' tall. just go with it. SOme grow 2' during flowering... you never know!!