You need to be more specific than "Western Societies". Both the average and median "age at first marriage" varied considerably across different parts of Western Europe and the American colonies in this period. The following in based onthe book The History of the European Family: Family life in early modern times (1500-1789), edited by David I. Kertzer and Marzio Barbagli

Contrary to popular sterotypes, young men and women in Early Modern Times had remarkably similar marraige patterns to the late 20th century -- The beestCanturbury, England in the 1690s, average age at first marriage was 26 for Women, and 28 for men. The medivan values are a little lower, but not much. In fact, age at first marraige seems to have reached a high of 26-30 for both men and women in the late 17th century, and then declined slightly over the course of the 18th century, by which point age at first marraige was close to 25 years old for men, and around 22 years old for women.

Keep in mind that these are averages. I havn't read that book in several years, but I also want to mention that this varied regionally as well as over time. Finally, most of these demographic data is based on church records of marragies, deaths, and births. Relationships that took place outside of the state appartus don't show up in our records, nor do the family lives of religious and ethnic minorities (Jews, Roma, Basques, Travellers, etc).

Also, this data really only applies to urban-dwellers in France, England, Germany, and Northern Italy. In other parts of Europe, and the greater Mediterrian basin, as well as in rural areas, there are some signs that these numbers are probably a little too high.

Basically, though, functional leigtimized teenage marraige was nowhere nearly as common as popular media suggests, at least for ordinary people in the period 1500-1800.

TL;DR: For Western Europe, mid-to-late 20s was common for both men and women in the period 1500s-1790s. However, the the discrepancy between the mean and the median suggests there's some important social and regional differences that complicate the picture.