At what point do you ask about their sexual past?

I ask this question because it matters to me personally. I'm a virgin so, in a perfect world, I'd prefer another virgin. Unfortunately, a body count of 1 or 2 isn't completely out of the question if being realistic I guess.

I'd really like to know early on so we can decide if we want to move forward or not. Not trying to be rude or impolite about it. I just don't want to waste anybody's time in the long run if I'm not comfortable with the circumstances. At what point, or stage, would it be best to ask?

[Disclaimer: This is not about if you don't like the question or if you think it's not anyone's business. A person has a right not to share their history with anyone. I respect that, however we should both be mature adults about it and politely part ways if we can't be honest or transparent about it.]
At what point do you ask about their sexual past?
Post Opinion