Nothing here is improvised. A go/no-go gate with pre-agreed criteria and a named decider, a minute-by-minute runbook with a rollback at every step, and a dual-run that means the switch is a formality, not a leap.
The gate
Criteria are agreed before the meeting, so the decision is reading the evidence, not debating the bar. One named decider — the executive sponsor — makes the call.
| Criterion | Threshold | Status |
|---|---|---|
| Financial reconciliation | Zero variance on all financial metrics | Pass |
| Open defects | No Sev-1 / Sev-2 open | Pass |
| Report parity | 100% of in-scope reports signed off | Pass |
| Rollback tested | Rehearsed in a non-prod dry run | Pass |
| UAT sign-off | All function SMEs signed | 1 pending |
| Support readiness | Hypercare team & runbook staffed | Pass |
The play
Every step sequenced against a T-clock, with an owner and a checkpoint. The freeze protects data integrity; the validation gate is the point of no return.
| T-clock | Step | Owner | Checkpoint |
|---|---|---|---|
| T-48h | Comms sent; freeze announced; support on standby | Change Lead | Acknowledged |
| T-2h | Source freeze — no writes to legacy EDW | Data Eng | Freeze confirmed |
| T-0 | Final incremental load; catch-up to freeze point | Data Eng | Load complete |
| T+1h | Final reconciliation — revenue to the penny | Testing / TPM | Go point |
| T+2h | Re-point reports & connections to Snowflake | BI Lead | Smoke test pass |
| T+3h | Open access to users; announce live | TPM | Live |
| Any | Rollback trigger: reconciliation fails or Sev-1 found → revert to legacy, unfreeze, stand down | TPM | Legacy restored |
De-risking trust
Both platforms ran in parallel and reconciled daily through the waves. By cutover, the target had already matched the source for weeks — so the switch removes the old system rather than gambling on the new one. Trust is earned before go-live, not asked for after.
An elevated-support window opens at go-live: a daily war-room, fast-track defect SLAs, and champions fielding questions inside each function. Exit criteria — defect rate below threshold and adoption climbing — must be met before hypercare closes and support normalizes.
Golden thread · go-live
At the T+1h gate, CLOSE_AMOUNT_USD reconciled to the penny against the frozen source — the same field that ran 6% high in test now matches exactly, because the grain and definition were fixed upstream. That single green check is what let the sponsor say go.