I decided to look into this based on some recent conversations. All I have looked at so far is the relationship between time of sex and long term relationship outcomes. There does seem to be a consistent relationship between waiting for sex and LTR success on multiple measures. This provides some evidence for the FDS "three month rule" as being a viable strategy for the kind of long term relationship FDS women want.

A summary:

Men and women both have more negative LTR outcomes if they had a higher N-count, earlier sex or earlier cohabitation. Also, if they had more relationships even without sex. These predict: shorter LTR length, lower emotional and sexual satisfaction in married couples. These associations exist for couples who have waited as long as two months for sex and one year for cohabitation. When controlling for common variables, the relationship still remains.

A history of short term hook-ups predicts bad marital outcomes specifically for men. For women, the same relationship exists, but mediated by communication (women with many hook-ups report lower communication).

Women with an anxious attachment style are more likely to have sex earlier, women with avoidant styles later. Women also do not interpret sexualization of an interaction as a sign of attraction, while men do (this may have implications for the three date rule as a sign of attraction).

Summarized abstracts:

For men and women, there is a negative shared influence for previous romantic, sexual, and cohabiting relationships on current relationship attitudes, sexual satisfaction, commitment, and stability. Also, a unique negative influence for previous sexual and cohabiting relationships on current relationship stability. Researchers concluded that positive lessons that are learned from previous relationship experiences are likely being overwhelmed by the negative carryover in relation to relationship stability.

https://psycnet.apa.org/record/2019-36933-003

Waiting to initiate sexual intimacy in unmarried relationships was generally associated with positive outcomes. The effect was strongly moderated by relationship length. Early sexual initiation reporting increasingly lower outcomes in relationships of longer than two years.

https://www.tandfonline.com/doi/abs/10.1080/00224499.2012.714012

Both structural equation and group comparison analyses demonstrated that sexual restraint was associated with better relationship outcomes, even when controlling for education, the number of sexual partners, religiosity, and relationship length.

https://psycnet.apa.org/record/2010-25811-011

(Communication mediates hooking up and marital quality for women; hooking up associated with negative marital quality for men.)

A theoretical model exploring the relationship between hooking up and marital quality and whether this relationship is mediated by sexual satisfaction and communication. Gender proved to moderated the association between variables, education did not. Hooking up has a direct negative relationship with marital quality for men, not mediated by sexual satisfaction or communication. For women, no direct relationship between hooking up and marital quality, but an indirect influence via communication.

http://krex.k-state.edu/dspace/bitstream/handle/2097/13349/MatthewJohnson2012.pdf;sequence=5

(Attachment and sexual timing - anxious women have sex earlier, avoidant women later. No relationship for men.)

Studies are beginning to show evidence of marital problems for couples that have engaged in early premarital sexual activity. Results show a significant, positive relationship between female anxious attachment and early sexual timing; a significant negative relationship between female avoidant attachment and early sexual timing. No results showed significant relationships between male insecure attachment and sexual timing.

https://scholarsarchive.byu.edu/etd/3889/

(Waiting two months was associated with increased satisfaction, longer relationships. Men and women. Anal counts.)

Young adults who waited more than 2 months to have sexual intercourse reported higher relationship satisfaction than those who had sex earlier. Young adults who had sexual intercourse after 2 months reported longer relationships than those who had sex earlier.

https://cdn.ymaws.com/www.psichi.org/resource/resmgr/journal_2017/SummerJN17_Vancour.pdf

(Men and women read attraction cues differetly)

Steering the conversation to the topic of sex signaled to men that their date was attracted to them. Women looked for different behaviors to infer attraction, such as mentioning future plans and kissing them goodbye.

https://link.springer.com/article/10.1007/s12119-015-9322-1

(Early cohabitation associated with lower odds of marrying.)

Transitions into cohabitation are most common early in sexual relationships; one-quarter of women cohabit within six months of sex. Women from more-advantaged backgrounds significantly less likely to cohabit, cohabit more slowly. Women who moved in within the first year of their sexual relationship demonstrated lower odds of marrying than did women who deferred cohabiting for over a year.

https://link.springer.com/article/10.1007/s13524-018-0649-8

Number of sexual partners is associated with lower levels of sexual quality, communication, and relationship stability.

https://onlinelibrary.wiley.com/doi/abs/10.1111/pere.12009

(Early sex associated with low marital quality, but only in women. Cohabitation is a major contributing variable.)

Rapid sexual involvement may have adverse long‐term implications for relationship quality. Delaying sexual involvement was associated with higher relationship quality across several dimensions. Speed of entry into sexual relationships was negatively associated with marital quality, but only among women. Association between relationship tempo and relationship quality was largely driven by cohabitation.