The slight recession in the temples tells me it's male pattern baldness, but theoretically your hair could stay like that for another 10, 15, 20 years, without anymore recession. Although the fact that it's started so earlier could be a sign of further loss to come sooner rather than later (but again you never really know), so I feel it's always a good thing to start treatments early if cost isn't an issue. Just be sure not to be shy with your dermatologist and ask all the questions you can. I'm pretty much in the same boat as you, I have a full head of hair with early recession in the temples and my dermatologist diagnosed it as male pattern baldness right away and prescribed propecia for me.