When should historical campaign performance be considered in media planning?

Considering historical campaign performance is crucial when establishing media mix allocation. This phase involves analyzing past data to determine which channels and strategies have produced the best results, allowing planners to allocate budget effectively across different media types. By examining how previous campaigns performed, media planners can identify which channels delivered higher engagement, conversion rates, or return on investment, thus maximizing the potential impact of the current campaign.

In contrast, the other choices do not specifically leverage historical performance to its full advantage. Creative development may benefit from insights gleaned from past campaigns, but it is not primarily focused on media allocation. Setting target demographics involves identifying the ideal audience but doesn't directly involve the analysis of what worked in previous media strategies. Evaluating performance after ad placement is too late to inform the current campaign's decisions, as adjustments should be made based on these insights prior to implementation, not retrospectively.