The lead time for a brand activation depends on the scale and complexity. As a rule of thumb:
Small scale (pop-up, sampling): 4 to 6 weeks
Mid-sized (experiential event, 50-200 guests): 2 to 3 months
Large scale (brand experience, 200+ guests): 3 to 6 months
Always start with the strategy: what do you want to achieve and for whom? Then comes concept development, venue selection, production and execution. A tight schedule keeps the process manageable.
Bring in an event agency early. The more time there is for concept development, the more creative and impactful the result.