I believe they have to be done in the order given on the scorecard. You should get someone at your school to administer the test, normally the JROTC instructor or a Gym teacher. They should have done this before. Good Luck!
It’s almost always in the sequence of pushups, sit-ups, mile. According to the regs, you can technically do the mile first and the other two events after but don’t count on anyone making that accommodation for you.