The appropriate age for a woman to lose the single largest multiplier on her other SMV traits, is whatever age she has developed a degree of strength of those qualities that independent of that multiplier, she could secure the commitment of a high quality man.

If you cannot win commitment without sex, don't expect sex to win commitment. For men - it's the opposite (if you can't see a way to get sex without pledging your commitment, don't pledge commitment)

Basically, there's no biological reason for a man to be interested in women except for the evolution of interest in the sexual resource. Women (and most men) cannot take the place of a man's own doership in his life with the same effort and competence (and most women would resent him if they had to anyway; only King like men can have others assume their doership and retain respect)

So, sex is pretty much the driving force behind male desire for women. That's just how it is.

A first-order interpretation of this situation would be (and this is what sluts have always done, and what the Sexual Revolution has made the default of almost all the West, while chemically uncoupling it from reproduction) :

"I am a woman, men's chief interest in any level of commitment to me is dependent on my sexual value - therefore to obtain commitment soon, I should use my sexual value soon"

Then there's all the momentum investor like valuation strategy backing up this FOMO - "omg, person X who is famous made this buy/sell on a stock so I think I should too!"

The time horizon on a woman's sexual value to men basically ends around 30, give or take (mostly give) 5 years.

Seriously - at 35, a woman's primary value being a sexual one means she's cultivated nothing else. It's a greatly depreciated asset at that point - better hope it was cashed out well by then. Shouldn't even be in the market!

But it starts sometime around 15 (no, I'm not advocating teenage girls have sex to secure commitment) and peaks sometime around 21 or 22 then plateaus and starts a rapid decline around 25. It's pretty much true that visible SMV for women is in relation to fertility.

Your question isn't just about fertility, though, it's about virginity.

So, male paternity (again, the promise of immortality comes though the female reproductive asset, the chief interest of men in committing in any way to women) is not a sure thing. Cuckoldry is an evolutionary strategy, our penises are still shaped to scoop competitors' semen out of the vagina, all men produce far more sperm than is necessary for monogamy, and women have hypergamous tendencies with what they find most attractive changing based on their hormone profile at the time (even birth control changes this).

So virginity, the status of a woman having copulated with other men (a man's real competition, not women -despite the contests inherent in mating) or not has an evolutionary role.

If she's not had sex with other men, and you keep having sex with her (consistently delivering your information of high quality, in every sense), there's a vastly more sure likelihood on the part of the male effort towards fidelity in his resource expenditure and return.

There's a reason the hymen is conserved across mammals that give live birth.

So age actually only starts mattering at the far end for women, in the sense that insofar as they seek long term, post-sexual peak commitment from a man like being married and raising kids well after being the most sexually desirable they were to a man who is also the father of those kids and who will keep having options (for example), their age at pregnancy matters (because ovarian reserve isn't infinite) and their age at which they use their sexuality to entice commitment matters (because men want sex with young fertile looking women, even if they haven't evolved to want children - they evolved to want that sex because Nature is a minimalist about this stuff)

Far end.

So for women, for whom the gift of male feelings of security (in mate loyalty and exclusivity) via virginity is unaccompanied by non-sexual SMV markers at an advanced age - virginity won't promise much to men with options.

For women, for whom that gift is accompanied by non-sexual SMV markers at any age - virginity acts as a multiplier (18 year old virgin girls are more common than 24 year old virgin girls - - but if a high quality man wants marriage and the 24 year old kept that same asset and learned to cook, clean, do laundry, be a soft place to land, etc.? She beats the 18 year old - in a way a straight competitors between two non virgins of those ages or an 18 year old non virgin and a 24 year old virgin with non non-smv skills wouldn't)

At no point should virginity (rather the sexual resource) be the only tool relied on in SMV for women.

For high quality men who are traditional: a virgin woman (even a young one) who can't stop nagging, can't cook, can't clean, can't do laundry, keep a home, hates kids, won't respect him, etc. isn't actually more preferable to a woman with an n-count of one or two or three (even an older one) who can keep a home, is sweet, is kind, defers, supports, advises, etc.

For high quality men who aren't traditional (think stereotypical RP), commitment isn't even on the table, even if enjoying deflowering conquests is.

Tl;Dr

You're not a man. Sexual experience doesn't actually appeal to men who want to commit, if you're not a virgin, keep your partner count as low as possible and work on everything else to raise your SMV and find a partner, at any age.

If you are a virgin, keep in mind that you shouldn't break that asset early on, but if you aren't raising your SMV for male commitment, that alone will be harder and harder to leverage in winning commitment as you age - so gather ye rosebuds! and get working on non sexual SMV factors, that you can use your virginity as a massive SMV multiplier when you go shopping for commitment.