Actually, it can cause your hairloss to become worse while you're on it. There's lots of who experienced worsening whilst on Finasteride. The drug does not respond positively to a lot of people.
There's been people on it for a year or more than 2 years and said there hair looked worse once they started taking Finasteride.
Also, it doesn't really look like you have hairloss before taking it. You might be experiencing what is actually known as a "maturing hairline" and not actually a receding hairline due to male pattern Balding. Often times that "Maturing hairline" will look the same for many many years with no receeding. And judging by the density, volume, thickness and shape of your hairline, it looks like you shouldn't even be worried about taking any drug for your hair, especially Finasteride which is making your hair look worse than what it was before you started, where you had negligible hairloss.
I would strongly advise you Google what a "maturing hairline" is, which is caused by age and not be confusing it with Male Patterned Balding.