T-Minus: the countdown, T-27 to T+30

Pre-flight, the five stages of the 27-working-day clock with their exit criteria and artifacts, the gates, the six workstreams, and how larger deployments add waves rather than longer phases.

The clock runs 27 working days from kick-off to go-live, then 30 days of coaching. Count working days, not calendar days, and load the customer’s public holidays into the Project Plans workbook’s Setup sheet so every task date is real.

Stage	T-days	Days	Leaves behind
Pre-flight	Before T-27	—	Everything the clock needs on day one
Discover by doing	T-27 → T-18	10	The Fit Ledger: every gap tagged Configure now, T-Plus or Not needed
Configure in the open	T-17 → T-11	7	A configured tenant, built daily with the customer watching and driving
Cutover, audited	T-10 → T-3	8	A reconciled cutover: trial balances match legacy line by line; the dry run timed
The Rehearsal	T-2 → T-1	2	A passed rehearsal: one real business day in parallel — the only go / no-go
Go-live	T-0	1	A live ledger: legacy read-only, first invoice before lunch
Coach in the flow	T+1 → T+30	—	An adopted system: hypercare absorbed into normal operations

Pre-flight: before the clock starts (proposed default)

T-27 is day one of the countdown, not day one of the relationship. Pre-flight is an addition to the published method: without it, the first days are spent chasing access instead of discovering by doing.

Commercial	People	Tenant	Data
Contract signed; audited revenue received	Countdown Owner named, with same-day scope authority	Onboarding form submitted: cloud, region, network, SSO	Read access to every legacy source system
Go-live date agreed and on the board	TRANXACT Flight Lead assigned	Tenant provisioned: three-node cluster, live within hours	Representative sample data extracted for discovery
Scope anchor: modules and entities for wave 1	A key user per process named and released for the countdown	Key users can log in	Cutover date and migration scope (as-of / period) proposed

How this fits the Technical Deployment Guide: its proposed build targets — onboarding form, design sign-off and a build from code of about five working days each, five more with Live DR — run before the clock starts. The countdown assumes the environment exists; that is exactly why the tenant is a pre-flight item and why T-Minus has no landscape-build milestone.

Treat any unticked pre-flight item as a reason not to start the clock.

Each stage, and how it ends

Stage	What happens	Exit criterion	Artifacts produced
T-27 → T-18 Discover by doing	Key users run their real roles against representative data in their own tenant; every discussion on a live screen; each gap logged and triaged; legacy extracts profiled; change impact captured as roles see their future screens.	The Fit Ledger complete and every line tagged; the Countdown Owner has signed wave 1.	Fit Ledger; Migration Object Register (draft); migration scope decision; Change Impact Assessment (first pass); stakeholder and comms plan; RAID log opened.
T-17 → T-11 Configure in the open	Daily sessions: chart of accounts, entities, currencies, roles, approvals, numbering configured no-code; ASK bulk-creates master data and drafts rules; configuration checks run as items complete; integrations built on APIs; mock load M1 prepared.	Every Configure-now line configured and checked in the tenant.	Configuration Workbook; Role & Adoption Readiness register; Test Plan (configuration and integration checks); M1 mapping signed.
T-10 → T-3 Cutover, audited	Mock loads M1 and M2; trial balance reconciled to legacy line by line; sub-ledgers tied to GL control accounts; a full dry run timed against the runbook; integration and role tests; rehearsal script prepared.	Zero trial-balance delta on the dry run, with audit trail; the dry run fits the cutover window.	Trial-Balance and Sub-ledger Reconciliations; Cutover Runbook with dry-run timings; Rehearsal Script; defect log.
T-2 → T-1 The Rehearsal	The customer’s own transactions for one complete day, by every person who uses the system on T+1, in their own role, with their action queue live; results compared with legacy; pass, or a short fix list executed the same day.	The rehearsal passes — the only go / no-go gate.	Rehearsal Script with results; Go / No-Go Gate record; adoption participation per user; final cutover plan.
T-0 Go-live	Legacy frozen and read-only at the cut-off; the final load repeats the timed dry run; trial balance reconciled and signed; integrations to production; users log in.	The first invoice posted in production, usually before lunch.	Cutover Runbook (final column); signed reconciliation; Hypercare Exception Log; KPI: days to first posted invoice.
T+1 → T+30 Coach in the flow	The queue surfaces each user’s real work and ASK helps them do it; a daily 15-minute hypercare standup shrinking to twice weekly and then into normal operations; T-Plus waves switch on deferred scope.	Exceptions trending to zero; hypercare absorbed into the normal rhythm.	Hypercare Exception Log; T-Plus backlog and wave plan; KPI Scorecard; adoption follow-up.

Gates (proposed default)

One formal go / no-go — the rehearsal. Every other gate is a checkable fact.

Gate	When	Criterion	Evidence	Decided by
Countdown start	T-27	Pre-flight complete; date on the board	Pre-flight checklist	Countdown Owner + Flight Lead
Scope freeze (wave 1)	T-18	Every Fit Ledger line tagged; wave 1 signed	Fit Ledger	Countdown Owner
Configuration complete	T-11	All Configure-now lines configured and checked	Configuration Workbook, Test Plan	Flight Lead
Reconciled dry run	T-3	Zero TB delta; sub-ledgers tie; dry run within window	Reconciliations, Cutover Runbook	Finance controller
The Rehearsal (GO / NO-GO)	T-1	Real business day passed, or fix list closed the same day	Rehearsal Script, Gate record	Countdown Owner
Go-live confirmed	T-0	Final TB reconciled; first invoice posted	Signed reconciliation, KPI	Finance controller
Hypercare exit	By T+30	Exceptions below threshold for 5 working days	Hypercare log	Countdown Owner + Flight Lead

Record every gate result in the Toolkit’s Go-No-Go Gate sheet with the evidence attached. Auditors and the steering sponsor read the evidence, not a status report.

Six workstreams, one clock

Workstream	Discover	Configure	Cutover	Rehearsal	Go-live & coach
Core implementation	Fit Ledger on live screens	No-code configuration daily	Configuration fixes only	Fix list same day	Same-week changes
Data migration	Profile sources; scope as-of / period	Mapping; mock M1 prepared	M1, M2, dry run, reconcile	Delta check	Final load, TB sign-off
Testing	Test plan drafted	Configuration and integration checks	Migration validation, role tests	Rehearsal = UAT	Exception triage
Adoption & training	Key users in their roles	Queues and ASK set per role	Users on rehearsal data	Every T+1 user rehearses	Coach in the flow
Change management	Change impact, stakeholders	Comms: what changes for me	Readiness pulse	Go-live comms	Reinforce; retire legacy habits
Technical & integration	Tenant live; SSO; access	API integrations built	Endpoints tested; DR drill	Production endpoints ready	Monitoring; hypercare

Scaling up: waves, never longer phases (proposed default)

Multi-entity and multi-module deployments repeat the 27-day countdown on the same ledger. Wave 1: the core entity with Accounting, CRM and Supply Chain. Wave 2: further entities and HRMS / payroll. Wave 3: Manufacturing, EHR or Student Lifecycle. Wave n: deferred Fit Ledger scope and new regions. Each wave switches modules and entities on as configuration toggles, so growth never triggers a re-implementation.

Plan wave 1 around the entity or process with the cleanest data and the most engaged Countdown Owner. Its success sets the tempo for the rest.

Values marked proposed default are the methodology’s recommended starting points. Confirm each one per engagement; the contract, order form and SLA prevail.

Take the course on this, with diagrams and a check