The first 100 days of an integration set the tone for the next decade. Move fast and you build momentum; hesitate and you lose talent, customers, and synergies. Integration planning is the bridge between deal close and value realization.

A great 100-day plan breaks integration into manageable workstreams—finance, IT, HR, sales, operations—each with clear owners, milestones, and dependencies. It identifies what must be Day 1 ready (payroll, benefits, communication) versus what can wait (system consolidation, org redesign).

But plans are only as good as their execution. Integration governance—steering committees, workstream leads, communication cadences—creates the accountability structure that turns plans into results.