When is the right time to introduce intimacy , Romantic relationship for our children?

I think the best time for such a discussion is in their teenage years and with an open mind, where consequences of bad actions in relationships are well known, and where they themselves will express themselves freely before anything goes wrong even when they come of age (18 years or 21 in some countries). The parent has to come as a friend in such situation and less of a protector, otherwise the child will be apprehensive even when they need help. My opinion.