Recognizing the importance of adaptation, previous studies have revealed substantial differences between native-born and migrant descendants in their reproductive behavior, sometimes aligning with behavior in the country of origin, and other times deviating from it. To gain insight into this puzzle, we make use of register data from Finland to analyze the timing of parenthood (first parity) of different groups of migrant descendants, in comparison to that of native-born individuals. Employing discrete-time logistic regressions, complemented by matching and mediation analyses, our research uncovers significant differences between migrant descendants with two foreign-born parents and those with one foreign-born and one native-born parent (2.5-generation), even when they partly originate from the same regions. Moreover, our study challenges the conventional choice of native-born individuals as the reference category, highlighting the importance of considering the unique urban profile of migrant descendants. The examination of the mediating effects of education and partnership status reveals that education does not appear to slow down the pace of female migrant descendants compared to native-born women. However, among male migrant descendants, higher levels of education correlate with a delayed age at which they have their first child, as compared to native-born men. Furthermore, we identify a substantial deceleration through partnership status for both male and female migrant descendants. This suggests that challenges in finding suitable partners in the host country can contribute to a delay in the age at which migrant descendants have their first child; a phenomenon that seems to extend even to those with one native-born parent.