Why the first 90 days are the whole engagement in miniature.
Everything about the next 12 months of a client-agency relationship is encoded in the first 90 days: the trust level, the pace, the measurement framework, the voice the agency uses, the problem being worked on, the senior partner's actual involvement, and the client's internal narrative about the agency. Fail the first 90 days and the renewal conversation is already lost.
Yet most agencies spend the first 90 days on "discovery", produce a thick strategy deck somewhere around day 70, and start "actual work" around day 90. This is backwards. By day 90 the client has already decided whether the agency is a strategic partner or a vendor, and the strategy deck arrives after the verdict.
The structure that works runs in parallel: audit, prove, strategise, operationalise. Each stage overlaps the next by two weeks, and the whole 90 days is designed to produce one visible, measurable outcome by day 42 — before the strategy deck exists.