Hi. The time to tell them is now!! Don't wait. You cannot have sex with anyone until you tell them the truth. Then its up to them to commit to you knowing the facts.
I speak from experience. I was married for over six years in the relationship for over 10 years. I have herpes. My wife DIDNT. She tested positive 2 months ago. We will be divorced soon. I have lost everything, My wife my kids , my home. All for not having the guts to tell her the truth. Dont go down the same road Please.