I am guessing you've already done things to prepare yourself for all sections of the CFAT and questions that may come up in the interview. If not, there is still time, and you can read plenty of advice on this forum.
If you're otherwise prepared, then here are some last pointers: Dress like you would to a civilian interview, it shows respect and shows that you're putting in effort. The other important point is how you hold yourself. Be professional and down to earth, and mean it. Do not lie. If you've done something that you are not proud of in the past, and it comes up, admit it and take steps to improve. This shows maturity. Don't make any excuses.
Treat everyone at the CFRC with respect they deserve. Best of luck.