I think you should mention it when it comes up conversationally. It would be pretty awkward to lay out all your sexual boundaries with someone who wasn't ever planning to pursue you like that. And you don't want the girl to think you are more interested in her hymen than in her heart. If it starts progressing that way, then you bring it up. For example, when invited back to her place, graciously thank her for the invitation, by let her know that you have made other choices in your dating life. Don't get all snuggled up within kissing distance if you don't wish to engage in that activity. Of course, if she's lamenting the lack of good virgins out there, then you can heartily agree.
Personal information like health or virginal status doesn't need to be shared with most people. I do, however, believe in full disclosure in all areas before marriage. In the sexual realm, that means number of previous partners, current STI screening, any related medical problems, and what a healthy sex life looks like to you. I would avoid unnecessary details of previous encounters because that's never helpful. Just be kind and appropriately honest.