First off, find some bait and fish on your graph, it's always better if there is something in the area to begin with. I start out dropping the lights just deep enough that the hull of the boat doesn't obstruct them. Then I like to start fishing just below the light or on the outer edges of the light. Most predatory fish feed "up", so you don't want to get below them. I usually run 3-4 rods at different depths and see which one gets the most action, then adjust the rest accordingly.
Also, when you start running your lights deeper, and I do when the water warms enough that the fish want to stay closer to the thermocline, you run the risk of a larger fish getting tangled in the chord and then you have to haul to whole thing up and untangle it all. Right now you shouldn't have any trouble getting the bait/fish to come up closer to the top. But even on consecutive nights in the same spot I've had to play around with the depth to zero in on the bite, often finding the best bite in an 18"-24" window somewhere in the water column. But once you get a good bait ball with some fish eating on them, and get dialed in on depth, it usually becomes a one rod tactic because more than that is just too much to deal with.
If you're not living on the edge, you're taking up too much space!