How to get driving test cancellations

So I had my theory test scheduled for November, only to have it changed three times. I paid and took my theory test today and passed, and have just seen that the next available test is in October where I'm at. What can I do to get the tests that people have cancelled since my driving instructor and I don't want to wait that long. In addition, I have never taken a test before so I am just eager to get it over with. Can I get a test before October?