Each year, the INS sets up a quota for issuing the H1-B. The quota period starts October 1st and ends at September 30th of the following year. If you apply for an H1-B visa after the quota has run out, your application will not be processed until the next October, when the INS resumes issuing another year's H1-B visas. If you are included in the current year's quota, usually you will get your H1-B visa in three or four months.