Start with a migration boundary
Decide which branches and workflows will move first. Name the person who owns each source file and who can approve the result. A website launch, a new till and a workshop change can have different cutover dates; the important part is knowing which system owns each record during the transition.
List what is in scope: active products, customers, price books, supplier references, opening stock, outstanding quotes, unpaid invoices and open jobs. Historical documents may be retained in a searchable archive rather than recreated as new transactions. Agree that choice before importing.
Clean the catalogue before moving it
Use stable product and supplier codes. Keep glass type, thickness, unit of sale, processing choices and supplier identity distinguishable. Resolve duplicates explicitly; two products with similar names may have different manufacturing constraints.
Prepare a small representative batch first: a stocked fitting, a sheet product, a configured panel, a trade-priced item and a discontinued line. Compare the imported records to the source before scaling up.
Reconcile prices and balances
Choose sample retail, trade and account-specific customers. Compare line prices, quantities, discounts, VAT, delivery and rounding against agreed examples. A matching grand total alone can conceal an incorrect line or tax treatment.
For stock, agree the count time and how movements after that time will be carried across. For balances and deposits, reconcile customer by customer and retain the original references. Do not treat an import as evidence that money has been collected.
Rehearse a complete order
Run a representative enquiry through quote, approval, order, purchasing, receipt, workshop, delivery and invoice. Include a partial receipt, a changed panel and an outstanding balance. Confirm that each team can find the same job and that the final documents match the approved specification.
Keep a discrepancy list with an owner and a resolution. Sign off the difficult examples before inviting staff to rely on the new system.
Cut over with an exit route
Agree the final source export, trading pause if needed, opening reconciliation and who can decide to stop the switch. Keep the old records available under the agreed retention and access arrangements.
After launch, reconcile the first day's sales, payments, stock movements and documents. Review unresolved imports separately from live orders so staff do not unknowingly complete the same job twice.