I've been in this situation, myself. I also gave it to someone else before I knew I had it and felt terrible about it.
Generally, though, there isn't much point in saying anything until it is clear you may be intimate. Since this is the moment to disclose birth control practices as well, you can bring it up at that time. A condom is pretty darn reliable (not lambskins but latex) in preventing the transmission of herpes but it might make oral somewhat less interesting for both of you.
So, when the time comes, you start by asking if she knows what herpes is. You might also have some literature available but make sure you know some facts! Also, there are medications that will pretty much eliminate outbreaks.
I've had it now for almost 30 years and only have outbreaks about once a year. It used to be every few months except when I was on the medication.
My wife is okay with it and, in 20 years of marriage, still hasn't contracted it. And we have unprotected sex. You have to be aware of the signs and alert to any possible transmission.