Just about every state requires you to be 18 to take an accredited FFI certification test. Your best bet would be to get a copy of the 5th Edition Firefighter Essentials and study guide workbook. Read through it and know it backwards and forwards. When the time comes you will be ready to ace the course.
I agree i was in much the same predicament. but any state you go to it is going to be 18 because the requirements for the FF1 is set on a national level.
i took it in New York at 16, also recieved National FF1 certification later that year. in NY you have to be at least 16 to participate in live burn drills and be on a Fire Dept.
It depends on your state. You should contact the state agency that oversees firefighter training and they will be able to tell you whether or not you can take the program before you turn 18.