In my experience with my setup,
I run at 100% and 24" seedling height. My logic is as the seedlings mature, they grow into more intense light, thus negating the need to adjust the light.
In such a large footprint, I agree with @99PerCent and @ReikoX
For reference, you're running at 480w at the Leds. Love the way it looks in your tent, looks like I did ok with spacing and distance Solid coverage there for how you have your plants arranged!