What’s a realistic timeline for a headless WP migration?

4 — 12 weeks. The variability is editorial parity, not engineering.

The 4-week migration

Single-locale marketing site, 4 — 6 templates, no e-commerce, no logged-in surfaces. Next.js front-end, ISR, image CDN. Possible if (and only if) editorial parity is established in week one — every existing component documented and reproducible in the new front-end.

The 8-week migration

Above plus two locales, editorial workflow with role-based access, third-party form integration, full structured-data round-trip. Two weeks of the eight are spent on editorial parity QA.

The 12-week migration

Above plus WooCommerce checkout (this is the variability), regulated-content workflows, multiple author roles, complex editorial states. The checkout flow is the long pole.

What blows the timeline

Discovering on week six that the existing site has a block the new front-end can’t reproduce. The fix is week one: catalogue every state, every conditional, every editor pattern. If you skip this, you’ll be re-quoting in week four.