Research Summary: Growth often requires start-ups to recruit new skills not present in the founding team. We analyze if the relationship between integrating new skills and growth depends on timing. Should new skills be recruited as early as possible, or can start-ups add them as needed along the way? Using a unique panel dataset covering Sweden's population of start-ups from 1997 to 2012, our analysis shows that (a) start-ups' growth rate is positively correlated with integrating novel skills early in their life, while adding novel skills later is associated with lower growth and (b) corporate spin-offs profit less from recruiting novel skills than de novo start-ups. We mirror our results against existing theories and develop theoretical perspectives for future research.