All up to personal discretion. Maybe reveal things in phases as the trust grows.
Well, I don't think you reveal it ALL right away.... but yeah, transparency is imperative
The key to any serious relationship is emotional intimacy which of course in a marriage extends to physical intimacy. In order for true intimacy to be existent complete transparency is absolutely necessary otherwise you're settling for a cheap facade.
The best definition I've ever heard for intimacy (sorry Mirriam Webster's is too vague) is being "fully known and fully loved" not just because of who you are, but in some ways in spite of yourself. As long as you are holding out about your past or putting on any form of facade of who you are today there will always be the question in the back of your mind if your partner truly loves you for who you are, or if they just love the you that you've allowed them to see and also the fear in the back of your mind that they may reject you if they were to find out what you're hiding. Personally when I was still single I would by far have preferred to be kicked to the curb because of my past than to be kicked to the curb because I didn't disclose my past and got found out.
By all means you need to use discretion as to how much information or even how much detail is handed out about your past how early in a relationship in the interest of letting someone get to know who you are now, but as a relationship progresses your partner has the reasonable expectation of knowing more information.