This is the 'doing' stage; working to achieve the milestones, monitoring, reporting and managing the work assigned.
The project manager works to achieve the agreed project deliverables according to the approved project plan and parameters within the project initiation document (PID). They will manage the work, which can be broken down into work streams or smaller work packages. They will report regularly to the project board on progress, this should include regular highlight reports. The frequency and format of reporting will depend on the project.
The key to good practice in project management, is 'no surprises' - good PMs will anticipate and manage problems before they hit. They ensure that any possibility of going off-track in terms of cost, time or quality is notified to the sponsor and project board at the earliest opportunity. In doing so they gain the sponsor and board’s guidance and support in dealing with challenges, issues and changing risks.
The PM should guard against 'scope creep' - it is usual for people to identify little extras and add-ons and want to include them. But little add-ons usually cost money and/or time and can have unforeseen consequences (risks). Capture them and use change control to seek a formal decision on whether to adopt them. If the board decides to approve the change, then the budget and appropriate resources, will need to be found by them and the planned timescales may need to be adjusted to accommodate. Ensure that key documentation is updated accordingly.