For light to be most effective, you want it to be bounced around, in an area that is optimal for the amount of Lumens you plan to use.
-Now, for optimal growth in flowering, you will need 5,000 lumens per sqft. This way, you can build the room to your light, or figure the Watts needed for your room.
-Your current setup is fine for Veg.

**Say you use the 3x8 area --> 3x8=24sqft x 5,000L = 120,000L
-Most400W= 50,000L
-Most600W= 90,000L
-Most1000W= 130,000L

-Or, just cut your space in half since you already have plans for the 400W.

And males will be easy to spot, youll have enough time to notice and pull before they drop pollen
Attachment 278088