Do you bring it up right away?
Do you wait until sex/fluid exchange has entered the conversation?
I wait until sex is a definitely a possibility before I reveal that I'm undetectable unless the question is asked myself.
I'm talking 99% online, I've thought about this some more since posting. Like most things in life, every situation is different. I rarely wait instead of telling early and often.
This is how I do it. I'd rather meet up online first. The very 1st line I say is that I am undetectable HIV+. If things then still progress, near the end of the conversation I reconfirm my status. When we meet up, I reconfirm my status yet a 3rd time. Reason being is it's a you said they said if it is just verbal. Maybe afterwards they felt guilty, then call the police and tell the police they found out from somebody else you were poz (even though they'd be lying) and you didn't tell them. Usually, the way it goes in court, you'd be the guilty one. By confirming online, I have it in writing that the court can see that I, in fact, revealed my status.