It does not start by itself after the 10 minutes... it will hang on the directions screen after the break is over. But I believe there is a time limit on how long you can stay on that screen before it will automatically begin the section and start eating away at your actual exam time. General consensus on some other posts is that you get at least another 5 minutes to sit at the directions screen before being penalized, but I can't confirm from my own experience.
The point is.. there's a little bit of buffer after that 10 minutes are up in case you have to wait a long time to sign out/sign in like I did on my test.