just read the following on embassy website.
You will receive instructions on how to proceed with a medical examination if needed. If a medical examination is required, processing of your application could take at least three extra months.
also,
Study Permits
Applicants should count, on processing taking a minimum - not maximum - of 4 weeks (excluding statutory visa office holidays) from the time a complete application is submitted at the Visa Section, to the time the decision is released from our office. As supplementary checks are frequently required, you should be aware that processing may exceed 4 weeks from the receipt of a complete application.