Bit late for cramming. But.... I would just say make a summary of what you have done. In my Religion class last year, we just had a year of overheads and waffle. But this year we're actually reading from the book. If you're reading from the book just make a bullet point summary of each paragraph. If you're doing pages and pages of overheads then underline the key points, this worked for me.
you should actually start at least two weeks before but when cramming in information can be very confusing some times you should have a notebook of all the key points of what you have learned though out the year. finding key points is a must