A 90-day plan for moving from client-side everything to server-side as the default. Each week has a milestone. The plan assumes a team of 2-4 people with 4-8 hours per week to spend on this.

Weeks 1-2: groundwork

• Audit current tags. The 30-minute audit is a starting structure.
• Document the event taxonomy.
• Identify the team member who owns the new infrastructure.
• Provision a SprTags container.

Milestone: documented inventory and a running container.

Weeks 3-4: custom domain

• Pick the subdomain (boring is good).
• Configure DNS, verify SSL.
• Update your CSP.

Milestone: custom domain serves traffic correctly.

Weeks 5-6: GA4 migration

• Add the GA4 client in sGTM.
• Run client and server in parallel for a week. Verify counts within 1 percent.
• Disable the duplicate client-side tag.

Milestone: GA4 fully server-side.

Weeks 7-8: Meta CAPI

• Set up event_id-based dedup.
• Configure Meta CAPI tag with hashed user_data.
• Verify in Test Events first, then production.
• Watch dedup overlap reach 80+ percent.

Milestone: Meta CAPI delivering 80+ percent dedup overlap.

Weeks 9-10: other ad platforms

TikTok, LinkedIn, Snapchat or Reddit if applicable. Same pattern as Meta with platform-specific fields.

Milestone: all paid social platforms running CAPI server-side.

Weeks 11-12: warehouse and webhooks

• Set up parallel BigQuery export.
• Wire up billing webhooks for purchase events.

Milestone: events landing in warehouse near-real-time.

Week 13: hardening and handover

• Set up monitoring on the tagging URL.
• Set up CI for workspace exports.
• Document the runbook.
• Train a backup person.

Milestone: server-side tagging is production infrastructure.

After 90 days

The migration is done. The discipline is ongoing: quarterly audits, monthly version reviews, an annual look at new destinations.