Small baby hairs in corners of hairline: receding hairline or just maturing?

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

In  my opinion, there are some simple things that you can notice. If your hairline is starting to look like a horseshoe pattern, it is most likely male pattern hair loss (Androgenic Alopecia) . If you're noticing that your hair is growing more slowly and that you are shedding more hair, it is more likely to be male pattern hair loss. Go to a hair loss expert and let them do a good history and examination , including magnified exam, to see if there is miniaturization throughout the scalp.PRP hair MD.com

While it is difficult to say without an exam, hair loss is often heralded by a change in the terminal to velus ratio. Terminal hairs are heavy and thick. Velus hairs are thin and feathery. The hallmark of a normal mature hairline is a higher ratio of terminal:velus. As the fraction of velus hairs rises, the likelihood of recession increases as well. However, this is not a judgement which can be made via a snapshot single point in time evaluation. The trend is most important. Rising velus numbers portends a greater likelihood of recession than a one time observation of "baby hairs."As always, discuss your concerns with a board certified plastic surgeon (ABPS) with experience in hair restoration.

 Your biggest enemy is the progressive thinning leading to a balding pattern that may not evident at this point in time. The degree of thinning that you are experiencing would suggest that you should see a doctor who most likely will get Bulk Measurements of your hair to determine the degree of the thinning that you may be presently having. If the diagnosis is early genetic hair loss (the most common cause of hair loss in young men and you are probably following your families balding problem), then the best treatment would be the drug finasteride which is highly effective in men of your age and may not only stop the hair loss but possibly reverse it. If you are developing a more advanced balding pattern the best test to get is the HAIRCHECK instrument test which will determine the Bulk Measurements of your hair and this will show, over a one-year time frame, how effective the treatment will be or if you are not on drugs, using this instrument to tell you if you have ANY hair loss at all.  Once you know this information, then you and your doctor need to develop a MASTER PLAN which will define what you need