.: so comes snow after fire :.

I think it's a good idea to postpone your CPE until December. After all, you're not in a hurry to get it, are you? Having more time to study means a better chance of getting top marks right on the first go, which is a good strategy. And if you're not happy with your final result, you can always sit for the exam again next year, being already familiar with the process. Anyway, knowing your language skills, I'm sure you'll do great the first time around! ^^