Jarrad, you know my status, so for the rest of you; I am HIV- and my partner is HIV+. He told me about his status right up front, on our first meeting. I was attracted to him, both physically and intellectually, so I didn't run for the hills like some people would. Boy, am I glad I didn't. We've been together for almost 7 years. I'm still negative, BTW.
I will not deny that his health has caused some problems in our relationship, but no LTR is ever perfect or without problems. When we met, and when I decided to continue seeing him, I knew I would have to modify my sexual practices, and that is a compromise I was willing to make. As for his longevity; the way I looked at it was, "Well, he or I could also get hit by a bus at any time..." At that time, I didn't care if we had a day, a year or a decade, I knew they would be good. And they have been.
HIV is not a death sentence, and it doesn't have to mean the death of your sex life either. Yes, it changes things, and that is a choice that both partners must make freely and with all the necessary information.
Back to the original question of when to tell; There is a point in every relationship, whether it is someone you meet in a bar or someone you've known for years, where one or both of your feelings may change from platonic friendship to sexual interest. It may be immediate (like with my hubby and me) or it might not ever happen at all. In my opinion, that is the point where you must disclose anything that should be disclosed.
If you have a platonic friend, you don't ever have to tell them unless there is a chance of their being exposed through some other event like an injury or if they want to use your toothbrush or fingernail clippers. On the other hand, if you pick up a guy in a bar for the intent of having sex, you really must tell them beforehand. Likewise, if your best friend whom you've never slept with suddenly comes on to you, that's when you have to tell them.
That's my considered opinion.
"That which does not kill us, surely makes us stonger." - Neitsche