It really depends on when you started playing violin and how much you play. When I entered freshman year, I was just finishing Suzuki Book 5, but I started playing violin at the beginning of 6th grade and actually started on book 2 when I began private violin lessons.
The Suzuki books are designed so that, with a moderate amount of practice, you go through the first few books at a rate of one per year, and then as your practice time increases, you go through them more quickly as you get into books 4, 5, 6 and so on.
I would say that as an incoming freshman, you should be somewhere in book 5, hopefully nearing book 6. If you're there or anywhere ahead of that, then I think you should be doing just fine in your school orchestra.
Hope that helps.