Write a runbook the team can follow under pressure. Include when entry in the old system closes, who checks the opening data, and which transactions must succeed before everyone starts using the new system.
Rehearse the switch
Run through the sequence with the people responsible for each step. Record timings, decisions, and dependencies. Practice how staff will capture transactions if the switch is delayed.
Set an escalation path
Separate issues that block operations from those that can wait. Assign a decision owner for each type, agree when to use the fallback procedure, and share that information before launch.
Illustrative photo by Luke Southern on Unsplash.