Run the journey against test profiles in your sandbox. No real sends. Validate the logic before activating in production.
For email content, send a test proof to internal addresses before activating. Verify rendering, links, personalization, and consent suppression.
Once a journey is activated, it starts processing real profiles in real time. Activate during low-traffic hours and watch the first hour of execution closely. The "running journeys" dashboard surfaces errors and unexpected drop-offs immediately.