Taking SAT Subject Test at Test Center

<p>So, I originally signed up for the US History Subject Test for May 1st. I went in and decided to take the Math 1 Subject Test as well. I realize that they bill you, but on my account on collegeboard it only shows my US History as completed. Do I have to wait for the bill? And how long will it be?</p>

<p>Any one know?</p>