Phased go-lives exist because switching off a working system is frightening. You run the old and the new side by side, move one area or one product group at a time, and keep a way back. That logic is sound on a brownfield site. On a greenfield site there is nothing to run side by side and nothing to go back to. The warehouse did not exist last month. The debate about big bang versus phased still happens, because everyone has had it before, but the thing it was about has gone.
What the question is really about.
Strip out the legacy argument and three things are left, and they are all about the operation rather than the system.
How the stock arrives.
A new DC fills up. Sometimes over a weekend from an old site that is closing, sometimes over months as suppliers are redirected and a network is rebalanced. If stock arrives in one movement, the system has to receive it in one movement and the go-live is a big bang whether you call it that or not. If it arrives over months, the system goes live on day one at low volume and the operation grows into it, which is a phased ramp without needing a phased design.
How the volume ramps.
A site that opens at full throughput on Monday needs everything working on Monday: every dock, every process, every exception path. A site that ships a tenth of its design volume in the first month can go live with the core flows proven and the edge cases still being finished, because the edge cases will not occur at that volume. Be honest about which one you are. Most greenfield sites ramp, and the ones that claim otherwise usually mean the sales forecast rather than the physical plan.
What customers were told.
If a date was given, the cutover has to be rehearsed for that date, and the rehearsal is where you find out whether it holds. A phased ramp behind a hard date is a big bang with a softer name.
The phasing that does make sense.
There is one kind of phasing worth designing for on a greenfield site, and it is not by area or product group. It is by process maturity. Go live with receiving, putaway, picking and dispatch proven on real product with the real team, and treat everything else, the cross-docking, the value-added services, the returns flow, the customer-specific labelling, as phase two, switched on when the core is steady and the volume is there to need it. That is not a compromise. It is the difference between a floor that learns one system and a floor that learns six things at once and trusts none of them.
What does not change.
Whichever way the stock arrives, the cutover weekend still has to be rehearsed end to end before it counts, with the freeze, the first receipt, the first wave and the first dispatch all timed and owned. The readiness gate still has to be measured against the floor and not the plan. And a senior consultant still has to be on the floor through the first weeks, because the habits that form in that period are the ones the site keeps. None of that is a big bang or phased question. It is a go-live question, and it is the same on every site we have stood on.
On a greenfield site the go-live approach is not a choice you make. It is a consequence of how the stock arrives and how fast the volume comes. Read those two honestly and the plan writes itself.
How Luminar approaches the go-live.
We ask for the stock plan and the volume ramp before anyone draws a cutover diagram, because those two decide it. We design the go-live around the core flows and hold the rest for a second phase that is planned, not improvised. We rehearse the weekend against the real opening date, and we say in writing if the date and the readiness have come apart. Then we stay on the floor. The runbook decisions themselves are in Cutover weekend.