are you counting your first 3 weeks just curious,some guys start flower at first bud,others just run 8-9 weeks when they start the 12/12,,I ask because I do not count the first 3 weeks or 21 days,when I have switched the light cycle,,a plant takes 21 days to go from vegg state to flower state,,during those 3 weeks is when your vertical push occurs,,I know all have there own way so I was just curious,as that will tell me some about your flower and their progress,I do soil myself mate but am curious on a hydro set up just never ran one,,,I will also add the only thing that I know of that can shorten flower is too much P or phosphorus can,,or if a plant is out of whack and stressed N,or nitrogen can make one finish to soon,or even seed a little and finish early but at suffering to the plant and quality of said finished product,just my 2 cents,I have some plants further along than yours right now,flipped my lights Feb 28th they may have 10 days left been looking at trics all clear and cloudy no amber yet,,Your plants look good look heathy