There are many factors that influence the length of your job search. Some things you can control and others you cannot. The best thing you can do for yourself is to start early, and there are plenty of ideas to help you in this section.
CareerShift lists some of the different methods you can use in your search. Many times students concentrate on using job board web sites and consider that several hours of applying on line constitutes a complete job search. Such thinking blinds them to a multitude of techniques that are available.