In my 20s. I suppose it's remotely possible that I contracted HSV since then without ever having any symptoms, but my understanding of HSV is that with all forms the initial infection is obvious so that's quite unlikely.
We're not talking about HPV, which I (and you) very likely have wether we know it or not, without vaccination.
I'll announce my scarlet letter to make a point. I was recently tested for HSV and came back positive for HSV-2. I've never been tested before so I have no idea how long I've had it, but it was a surprise because I've had zero symptoms. In fact, I figured it was a false positive so I got re-tested.