Through the class, I was well aware that project team sets early start day, early finish day, late start day, and late finish day when scheduling tasks. By what criteria are early start days and late finish days determined?
I had some experience with this during my senior Capstone, where we had to create a Gantt chart to map the critical paths for completing our project. In task scheduling, early start is the soonest date you can begin any aspect of the project. This is usually dependent on the Design Development Plan (DDP) and the resources available at that time. Late finish is the latest date by which an aspect of the project will be completed which typically depends on delays in proceeding tasks, Murphy's law, or other pitfalls having to do with costs, resources, and risks. These determinations are subjective and highly situational but a staple in current good manufacturing practices (cGMP).
I believe what you are describing is "slack". The difference between the earliest finish and latest finish can be calculated by measuring your skills, workload and external project variables honestly. If a task will take 1 day to complete, but you know that part of this task requires outside resources who are slow to respond the slack for this task could be an extra day to allow for the possibility of this outside resource running slower than your own personal timeline. If you are very busy at the moment, a default amount of slack may be 3 days to any additional task. Similarly if you are not very busy, the slack for each task might be only a day or none at all. Calculating slack is somewhat of a subjective skill and requires the project lead to be honest with their team's ability to handle a project while also taking in account outside variables.
As a person without experience, from my understanding the early start date is heavily determined by the dates set in the critical path whereas the late finish date depends on all paths. When multiple paths are presented, the early start date is selected by the early date of the critical path since this path holds a longer duration. On the other hand, the late finish date is determined by the late start date of all paths. A longer path, or the critical path, will present an earlier start date than other paths but essentially each path will have the same late finish date.
