The 90-Day Window
SHRM: structured onboarding increases 3-year retention by 69%. Engineering-specific onboarding should include: codebase orientation (week 1), first meaningful contribution (week 2-3), full feature ownership (month 2), and first architecture review (month 3).
Investment: 40 hours of team time per new hire ($5K). Return: 69% retention improvement = $138K saved per prevented departure (at $200K replacement cost).