Often that is the key for procrastination. Procrastinators have a unrealistic view of the time needed to complete a job/work or a project.
Inevitably, this lands them in all sort of mess. Firstly, the job will be rushed which in turn affects the quality and criticism is sure to follow a shoddy job.
No wonder the next time you have to do something similar, you procrastinate. For one, you have no conception of the amount time required for the job, two, you have lost faith that you can turn in a good high quality work and thirdly, you are sure that it will be criticized. Therefore, what do you do, you procrastinate and try to avoid the unpleasantness.
As a first step, develop a clear and realistic perception of the time needed to complete your work. Once conceive that then the rest will follow.