Instrumenting a site before launch

A retailer was rebuilding its site, and, as usual, tracking had been pushed to "after launch." It is the fastest way to lose the first weeks of data, the exact period when everyone wants to know whether the new site is working.

The reasoning behind starting early is simple: without a measurement plan tied to real business questions, any implementation just collects noise. So the work began from the questions, not the tags. Each thing the business needed to know was mapped to a user action, and each action to a specific event and its parameters, before a single tag was built.

That plan became a contract. The dataLayer specification was written the way you would write an API contract, so developers knew precisely which event fired on which action, with which parameters and what naming. It was implemented in GTM and checked end to end in Preview and DebugView ahead of go-live, with consent handling aligned to GDPR from the start.

The site launched with clean, decision-ready data from day one, and nothing critical to retrofit later. The habit behind it is worth more than any single dashboard: treat the tracking plan like a product spec, design it before you build, and the data is trustworthy the moment you need it.