Here's what you need to know:
You need your social security number in order to take the test.
More than one section may be taken on the same day or each section may be taken on a separate day.
The test is not timed. You should allow at least an hour per section.
Come at the scheduled time.
You will get your score report for the Math and Reading sections the same day you take them.
You will get the results from the writing section about a week after it is submitted.