Balding or Mature hairline (Photo)

This requires an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or Hair transplantation. See an expert. Best, Dr. Emer

As men mature often their juvenile hairline may recede a little bit. From the picture your hairline appears appropriate for the male aesthetic, however this is best determined by personal preference and a professional evaluation to find whether or not miniaturization exists. If so, perhaps early intervention with medical therapy may be the appropriate course of action.  

That is not a hair loss because of ongoing process of androgenetic alopecia but  your natural frontal hair line or maturing of frontal hair line.  That is seen almost every young boys almost between 16-21 that have a very rounded hairline without recession in the corners.  Recession in the corners is a sign of mature pattern male frontal hair line.

Although it's difficult to assess from your photo, you should look into laser hair biostimulation.  It is very effective and helps to strengthen hair overtime, stop shedding and provide natural hair regrowth with continuous use. One good laser to invest in is LaserCap.

If you feel your hairline is thinning or receding, it is important to get on a preventative regimen. You should switch to an organic shampoo. You can also consider a natural DHT blocker like Saw Palmetto. There are also medications like Finasteride (a DHT Blocker) and Minoxidil (Rogaine) that can be very helpful in maintaining you existing hair, helping to prevent future loss and even regrow some hair. Before taking any medications you should discuss this with your general physician.

looks like you have a little loss on the left side. You might be a candidate for a PRP injection which will stimulate new growth and probably should be on Finasteride.

Your hairline appears to be largely intact, although the area left of center is either a natural variation or has shedding. It is best for you to consult with a specialist for full evaluation of your scalp.