Helene, Dont worry at all. I did mine at the beginning of May and as long as you you have done a little prep you will be fine. What I found really helpful was on the IELTS website you can find the mark scheme where they lay out what you need to do to reach a level 8 for example. Once I knew what they would be looking for, it made it a lot easier as I just kept that in mind when answering. I made sure I used lots of long words in my writing to show my 'superior' English skills! :D
Regarding the listening, just make sure you listen very carefully as it does try and trick you at points but as long as you take your time and listen carefully you will be fine.