Go live with everything on one weekend, or finance first and operations later? Both work. Both fail. The honest trade-offs, the question that usually decides it, and the one phasing that almost never works.
Every Business Central project has to answer this early: do we go live with everything at once, or in phases? Partners tend to have a house preference, and sales teams prefer whichever is shorter on the proposal. Neither is a reason. Here is how to think about it.
Big bang: finance, sales, purchasing, stock, warehouse and (if you have it) manufacturing all go live on the same weekend. One cut-over, one set of opening balances, one hypercare period.
Phased: usually finance first (G/L, debtors, creditors, bank, fixed assets, with sales and purchase invoicing), then operations (stock, warehouse, manufacturing, full order processing) a few months later. Occasionally the other way round, and occasionally by company or site rather than by function.
Can finance go live on its own without a bridge that is harder than the project? If the old operational system can keep posting invoices and stock movements and you can journal the results into Business Central monthly, phasing is cheap and safe. If every sales invoice has to flow from the old order system into the new ledger in real time, the bridge is a project in itself and you should go big bang, or phase the other way.
A second question: how many people does operations touch? Ten warehouse users and no manufacturing: big bang. Eighty shop-floor users across three sites with routings and subcontracting: phase it, and give operations the time it needs.
| Business | Usually |
|---|---|
| Up to about 30 users, standard stock, no manufacturing, from Xero/Sage 50/QuickBooks | Big bang. Small enough to do in one go, and phasing costs more than it saves. |
| 30 to 100 users, real warehouse, light assembly, a few integrations | Either. Decided by the bridge question and the team's capacity. |
| Manufacturing, directed warehousing, EDI, multiple sites | Phased: finance first on a quarter boundary, operations when it is ready, and not before. |
| Multi-company group | Phased by company: one company end to end as the template, then roll out. Not by function across all companies. |
Operations first, finance later. It sounds attractive when the warehouse is in pain and finance is coping, but every operational transaction has a financial consequence, and running stock in one system and the ledger in another for months means reconciling the two by hand every month-end. Finance first is the natural order because the ledger is where everything ends up.
The other one to avoid: "phase two" as a dumping ground. If every awkward requirement is deferred to phase two, phase one goes live without the things the business needed and phase two never gets funded. Phase two has a scope, a date and a budget on the day phase one is signed off, or it is not a phase, it is a hope.
Whichever you choose, the go-live itself runs the same way; we wrote up the weekend hour by hour. If you want help deciding, it is a one-hour conversation with the process map on the table: book a call.
