As a European I was initially puzzled by the bizarre US pseudo-rule “third date” concept but finally I realized it was a way for people to reduce the anxiety and guilt that seems inevitably to accompany any form of sexual intimacy in the USA. In more adult societies the question of when to have sex for the first time is very simple: as soon as both parties feel like it. Sometimes it’s just sex, sometimes it’s the start of a new relationship. As long as it’s pleasurable and consensual, who cares?