Why do treasury implementations run late?
Because the work that looks technical is short and the work that looks administrative is not. Connecting a bank and reading a ledger extract are engineering problems with known shapes. Deciding which entity owns a shared account, or what counts as an internal movement, is a decision about how the group runs, and it is usually being made for the first time.
Those decisions surface in a fixed order and each one blocks the next. Nobody can classify movements until somebody says what the categories are. Nobody can approve a payment path until somebody says who approves. A plan that puts these in a “configuration” phase near the end has scheduled its riskiest work last.
The pattern repeats often enough to plan around. Where a rollout slips, look for the decision that has been open the longest rather than the integration taking the most effort.
What actually happens in the first weeks?
Data arrives and disagrees with itself. That is the point of the exercise, and a project that produces no disagreements early has not looked hard enough yet.
Statements come in for the accounts somebody remembered, and the list turns out to be incomplete. The ledger extract carries entities that were closed and misses one that was opened. Two banks use the same reference field for different things. Every one of those is cheap to fix in week two and expensive to discover in month six, which is why the first weeks are deliberately spent breaking things.
The useful signal at this stage is not how much reconciles. It is whether each thing that does not reconcile has a name. A run that produces one number and a shrug has told you nothing; a run that produces a list of differences with a reason on each one has told you exactly what work is left.
Which decisions belong to you rather than to the vendor?
Anything that encodes how your group operates. A vendor can tell you what the system does with each answer; only you can give the answer, and pretending otherwise is how a configuration ends up being somebody else’s guess about your business.
The recurring list is short. Which accounts belong to which entity, and who is allowed to see them. What makes a movement internal rather than external. Which counterparty names are the same company under two spellings. What difference is small enough to pass without a person looking, which is a threshold you set with your auditor and never one a vendor sets for you.
Write the answers down before the build, even where they are provisional. A written provisional rule can be changed in an afternoon; an unwritten one has to be rediscovered from whoever remembers it, and that person is on holiday in the week it matters.
How do you tell early whether it is going well?
Ask for the exceptions rather than the coverage. A demonstration of what matched is showing you the easy half. Ask to see the lines that did not, and whether each one carries the records behind it and the reason it was held.
The second check is repeatability. Run the same period twice and compare. A process that produces the same answer both times, from the same inputs, is a process. One that produces two answers is still a person with a spreadsheet, wherever it is hosted.