The best time to bring the in-house audience insight team into a campaign is:

Bringing in the in-house audience insight team after the brand initiative kicks off allows them to analyze real-time performance data and audience reactions. This enables them to provide actionable insights based on actual campaign engagement, rather than pre-launch assumptions. These insights can then be used to optimize the campaign while it's still running, or to inform future strategies. Bringing them in simultaneously with the campaign launch would mean they are just observing without initial data to analyze, and at the conclusion of the campaign would be too late to make any in-flight adjustments, limiting their impact to post-mortem analysis.