This presentation offers a comprehensive overview of SLSP's strategic planning for transitioning to the NDE Primo user interface. It details a phased timeline with key milestones, alongside technical and communication plans designed to engage key stakeholders throughout the transition. The presentation will also highlight resources developed to meet libraries' needs and expectations, outline a system for collecting and processing feedback from library staff on the new UI, and discuss measures taken to integrate accessibility and usability testing into the process. Additionally, it will cover strategies for ensuring go-live readiness to ensure a smooth launch. By the end of this talk, attendees will gain a clear understanding of the planning process and leave with practical tips and a customizable plan to support their own libraries through this change.