The start dates of intensive and standard language courses are generally flexible. If you have some basic knowledge of the language, you will be able to start any Monday of the year at almost any school. If you are a total beginner, courses usually start once or twice a month.
You should be aware that language schools have more students in July and August, than during any other time of year, which means that course fees, housing prices and the overall cost of living are often more expensive during this time. If you would like to book a course in July or August, you should do so very early: schools have limited spots and might be booked well in advance for the high season. Your chances of getting your preferred housing type are also much greater if you book your course early. Housing options near the school are especially difficult to secure in the summer and tend to fill up quickly.
Language courses during the low season (September to June) are not only less expensive, but also have smaller classes. If you are able to wait to take your courses during this time you will pay less for your courses, and may even receive better housing since demand is much lower.