When I was doing the english test and they called my number, from the moment I stand up until the moment i went back to my seat, I smiled gently (not a huge fake smile) greet them pleasently and said thank you. They screen how you handle that situation, if you are confident enough not to be afraid of them, or if you feel overwellmed by them, you may not notice it, but just a single mocking face will make you out from this stage.
I just turned my mind off on the situations and treat them as friends (always respectfully).
OH! I'm 99.9% that i heard you can go whenever you weant, there's no need to wait 6 months whatsoever.