If memory serves me correctly, there is a short survey after you complete the last question and then your scores are revealed on the screen prior to leaving the testing room.
Then the Prometric staff prints it out, stamps it and you are good to go.
Well, you get your score right away, but it takes 2-4 weeks to "verify" your score wasn't reported incorrectly and to send it to AADSAS. Don't worry though, I've never heard that happen.
Just to qualify---it's available every day that the testing center isn't already booked for other testers. It's not likely that if you signed up today that there would be a spot on Tuesday, for example, and it takes a couple days to get your information to actually sign up for the test so plan ahead and sign up early.