A proper planning is one of the main issues the success of a software project lies on. However, a perfect planning is not useful without monitoring sufficiently, which involves not only controlling that the activities and expected costs are being met properly, but also having the ability to anticipate the impact that deviations from the plan will have on the future development of the project.Monitoring methods that can be found in literature, can obtain stationary photos of the status of a project at any given time of its evolution. They also allow planning which will be the result in costs terms and final project time obtained from these stages points, though they do not tell us how the project will evolve from the time when we are auditing to completion.By using the family of curves called sigmoidal or S curves, parameterized properly and using monitoring technique EVM (Earned Value Management), the project evolution is mathematically modeled as a continuous function, which allows not only getting a picture of it but also a movie that show the full evolution to its final draft.In order to validate the proposed function, show will use a set of projects in the area of software development with different characteristics that allow the proposal address to face up to a wide variety of situations. All these projects come from the real worldwide, and we proceed with two experiments these projects come to validate the proposals of the paper.