Due to scarcity of research about men, gender differences in transition to adulthood in Sub-Saharan Africa remain poorly documented. We adopt a novel perspective on this topic by examining gender gaps in the ages of first union and sex in 27 countries, focusing on measures of central tendency and dispersion. Gender differences in the age of first union decreased, driven by postponement among women with relatively late pattern of union formation. Due to concurrent persistence of very early unions among a sizable portion of women’s populations, within-country heterogeneity in the ages of first union increased substantially among women. Hence, although forces responsible for earlier union formation among women than among men are weakening, these changes affect population strata unequally. Gender differences in the age of first sex decreased to a lesser extent, but in some countries, they disappeared or reversed, suggesting a shift in the relationship between gender and timing of sexual initiation. Changes in partnership formation are more heterogeneous across countries among men than among women, indicating that timing of transition to adulthood among men is more context specific. We show importance of including men in research on partnership formation and exploring heterogeneity in this process both within and between populations of women and men.