Yours looks good to me already, but most don't get really dark until at least 5". and then even better at 8"-10".
And much has to do with the color of substrate and background. If you have a white, or pale background (normal colored neutral painted dry wall), and substrate, most cichlids will instinctually (like chameleons) blend to match the color are a defensive measure.
Note the dark (10") male on the right defending his dark cave.
But below similar size individuals hovering over light rock formations in Cenote Cristalino in Mexico.
in my video (in the link below) you first see dark individuals living in the shadow of overhanging plants and stairway, but later in a bright area (around min 2:50) they are much lighter in color (and also younger) maybe at most 3-4"
Eden2
