Some b-schools specify a minimum work experience of 2 years where as others do not state but do prefer at least 2 years of work experience. However, you have to keep in mind that the average work-experience at most globally ranked b-schools ranges between 48 and 75 months (counted till the time of entry into the MBA program). Therefore, once you have completed around 2.5 years in your jobs, you can start applying since you will enter with 3.5 years of work-experience (because round 1 deadlines are scheduled around one year before course commencement)