Project Schedule Management involves the processes needed to manage the timely completion of a project. It encompasses a range of tools and techniques that allow the project manager to visualize, quantify, and manage project timelines and milestones. The purpose is to ensure that the project is delivered on time without exceeding the planned resources. It includes defining and sequencing activities, estimating durations, developing and controlling the schedule.

An important aspect of Project Time Management is Resource Optimization. It involves allocating resources in a way that minimizes project duration and cost while maximizing productivity. This can be achieved through various techniques such as resource leveling and smoothing. Resource optimization plays a key role in helping project managers ensure on-time project completion by effectively handling potential resource conflicts and shortages.

Defining activities refers to the process of identifying and specifying the activities necessary to deliver the project's scope. It's about naming the specific actions required to produce the deliverables included within each work package. The approach to defining these activities should be appropriate to the nature of the work, the level of detail required, and the level of control required. This process often employs techniques like decomposition, rolling wave planning, and expert judgement. Despite its simplicity, defining activities is potentially on the most critical of project time management processes, as unidentified activities can lead to download errors in scheduling, cost estimating, and risk management.

Sequencing activities means identifying and mapping the relationships among the project activities. The sequence of activities is determined based on their dependencies, which can be mandatory (inherent in the nature of the work), discretionary (preferential or best-practice sequence), or external (depending on a factor outside of the project). A typical tool used for this process is the Network Diagram, where nodes denote activities, and edges denote dependencies. This process directly affects the project schedule and has a big impact on project risk, as a mistake in sequencing can lead to increased project duration, costs, and risks.

Estimating activity resources means determining what resources are required (materials, people, equipment, etc.) and in what quantities for each activity. This process is crucial as resources often have cost implications (ownership cost, rental or usage fee, etc.) and availability constraints. Techniques like expert judgement, analogous estimating, parametric estimating, etc. are often used to estimate activity resources. Making realistic estimates helps in achieving project objectives such as cost, time, and quality.

Estimating activity durations means accurately determining the number of work periods needed to complete individual activities considering all the resources available. Various techniques are used in this process including analogical estimation, parametric estimation, bottom-up estimating, and three-point estimating. Accurate duration estimates are crucial in developing a realistic project schedule. Misestimated activity durations can lead to project delay or cost overrun.

Controlling schedule involves monitoring the status of project activities, updating project progress and managing changes to the schedule baseline. The aim is to ensure that the project remains on track and is delivered on time. Failure in schedule control can lead to project delays, cost overruns, and unmet objectives. To control the schedule effectively, the project manager must use project management software, apply a performance review, and use project forecasting methods, among others.

Project float, also known as slack, pertains to the amount of time that you can delay a task without causing subsequent tasks to be delayed, or the project finish date to be affected. This tool provides flexibility in the management of timelines and resources, and allows project managers to reallocate resources from non-critical tasks to critical ones, should the need arise. Float is used heavily in scheduling and risk management, and represents a critical aspect of successful project time management.

A Gantt Chart is a visual tool in project management that helps in the planning and scheduling of projects of all sizes. The chart's horizontal axis represents the total time span of the project, broken down into increments (for example, days, weeks, or months) and the vertical axis represents the tasks that make up the project. By plotting tasks on this chart, with task durations represented by horizontal bars, project managers can get a visual on the project timeline, task dependencies, the start and end date of each task, and the overlapping of tasks. They are a crucial tool in project time management and help communicate what needs to be done and when, ensuring team members are on the same page.

Critical Chain Project Management (CCPM) is a method focusing on resource utilization over activity ordering. It challenges traditional methods by considering resource constraint and incorporates buffers to protect the project schedule. These buffers are integrated at different points in the schedule where a chain of dependent tasks exists to prevent delays. Unlike traditional methods that build individual task buffers, CCPM aggregates all buffers and strategically places them where most required. This allows for more efficient use of resources and more realistic schedule management.

Rolling Wave Planning is a project management technique that involves planning in waves as the project unfolds and details become clearer. It is a form of progressive elaboration, which means the planning is iterative and changes as more information is gathered throughout the project lifecycle. Initially, high-level planning is done based on the known information and as more details are available, the planning is updated and detailed to reflect the current understanding of the project.

Program Evaluation and Review Technique, commonly known as PERT, is a statistical tool used in project management, which was designed to analyze and represent the tasks involved in completing a given project. PERT helps to identify the minimum time for completing a project along with the potential risk areas. It encompasses the creation of a graphic representation of a project's timeline allowing the management to organize and coordinate tasks within the project. PERT analysis also involves the estimation of time to each project stages with some allowances for risk.