How does it work when you take multiple tests in one day?

I’m signed up for SAT Subject Tests in Math II and Physics, both on June 6th.
How does that work? I’m supposed to arrive at 7:45 and testing begins a bit after that. How am I supposed to take multiple tests on that same day?
Can someone please explain what I will experience?
Any input is appreciated.
Thanks

Each test is only an hour long. You can take one (leave two hours early), two (leave an hour early), or three (leave on time).

They give you a big book with all the tests in it. When time is called, they make you move on to the next one you’re taking.

There’s usually a short 5-minute break in between tests so that test takers who wish to leave can do so. But yeah, basically what bodangles said.