Stack migration has a reputation for going wrong. Usually because teams try to do it in a weekend, or because they migrate everything at once, or because they skip the parallel run that would have caught the breakage before it went live. The teams that migrate cleanly do one thing differently: they treat it as a controlled engineering process, not a switchover.
Here's how the 30 days should run.
Days 1–5: Baseline#
Before you touch anything, snapshot the current state. Active campaigns, lead flow metrics, conversion rates, CRM field mapping, active automations. Every workflow, every integration, every scheduled email, every field dependency — documented. You cannot claim you didn't break anything if you didn't know what it looked like before you started. This is the most underestimated phase of any migration.
Identify your system of record for each data type: leads, opportunities, customers, campaigns. This is the single source of truth everything else syncs to. If it's unclear now, it will be catastrophic after migration.
Days 6–15: Parallel run#
Set up the new platform with the same data model as the old one. Mirror your three highest-volume workflows — not everything, the three that matter most. Run both systems side by side for seven to ten days. Compare outputs. Anywhere they diverge, you have a hidden configuration issue. Find it now, not after cutover.
The parallel run is where most migrations skip to save time. It's also where most migrations that go wrong failed to invest. The seven days of parallel operation is not optional.
Days 16–22: Cutover#
Migrate one workflow at a time. Start with the lowest-risk — a dormant re-engagement sequence, not a live campaign. Monitor each cutover for 24 hours before moving to the next one. Do not chain cutovers on the same day. If something breaks, you need to know which migration caused it.
Keep the old system in read-only mode for reporting continuity. Don't turn it off yet. You'll need historical data accessible for at least 30 days post-migration to answer any attribution questions that come up.
Days 23–30: Harden and decommission#
Document the new system as if you'll need to onboard a new operator next week. If the documentation isn't clear enough for someone who wasn't involved in the migration, it isn't done.
Decommission the old system only after seven days of clean operation in the new one. Cancel contracts on the renewal date, not before — you may need access in a dispute.
The four pitfalls that derail migrations#
Big-bang migration. The cost of one missed automation cascades. Phased migration is always less painful than big-bang migration, even if it feels slower up front.
Skipping the parallel run. “We'll fix what breaks” as a migration strategy guarantees something breaks during a live campaign at the worst possible time.
Migrating workflows you didn't actually need. Use the migration as an audit. If a workflow doesn't justify the rebuild effort, don't migrate it. This is the forcing function to eliminate the cruft that's been accumulating for three years.
Forgetting reporting continuity. Historical campaign data is the most-cited reason teams keep paying for a tool long after they've stopped using it. Plan your historical data access before you pull the plug.