Scar revision for depressed scar of forehead would be best done with proper excision and closure without z, w, or other closure with added lines. It will not get better with more time except for the redness
If you are looking for a permanent solution, it appears from the limited photos that you will need a scar revision. Scars are noticeable for 3 reasons: 1) color 2) width and 3) depression/elevation. To minimize the appearance of a scar, you want it to be pencil thin, flat with the surrounding tissue, and as close to color as the surrounding skin. Most of this is surgical technique dependent, but in my office we also recommend post surgical anti-scar treatments to minimize visibility. Please consult with a board certified specialist who can assist you with achieving the results you seek.