In the scenario where a contract is required immediately, contrary to the initial plan of requiring it 3 months prior to the project's finish date, the project manager should request the team to initiate a change request. This is in line with best practices in project management, which call for formalizing changes through documented procedures. A change request is necessary to adjust the project's scope, schedule, and costs accordingly. It ensures that all stakeholders are aware of the changes, agree to them, and understand their implications. This process is part of the integrated change control process, which is crucial for managing contracts and any changes that occur during project execution.
References: (PMI's Guide to the Project Management Body of Knowledge (PMBOKGuide) and Professional in Business Analysis Reference Materials)