The format of the test and the material on it doesn't change much from year to year, so you should be fine starting to study now. Since you're going to take a class, I don't necessarily think you need to do loads of studying from the outset. I think the best thing you can do between now and your class is review your math and grammar fundamentals. You don't even have to do actual GMAT questions; working out of an algebra workbook, for example, will pay big dividends down the road.
Jim S. - Veritas Prep GMAT Instructor (Los Angeles, CA)