looking for input

this is my first time growing and I'm using hydro to boot. I have an igs drip system which is 3x3 and holds 20 1 gallon pots with a 1000 watt hps and a couple florecents on the sides. right now i've had them on 24/24 for exactly 3 weeks.. from my knowledge their looking great all a little over 1 foot and fairly bushy.. i was planning on changing the resevoir today adding ionic boost to the solution and cutting back the light to 18/6 for a week and then 12/12......I only have 4 feet from top of pot to light and want to maximes my space to its fullest.... i will add pics so that you can give me the best critizing possible if i can find out how too
- how tall should i grow them before flowering to maximes space
- how well are they doing/ am i doing anything wrong
- how much am I expected to yeild
FYI i am growing 4 blueberry and 16 bc big bud

i guess everyone forgot the part where i asked for input

how tall should i grow them untill i begin flowering.......I have 4 feet between top of pot and light im thinking foot and a half or soo

They will grow another foot or more during flowering. Watch the temperature at the top of the canopy and don't let it get to hot. You can always bend them if you need to keep them under the light.

thank you zandor much appreciated