I'm refering to my pivotal event as the climax. Its the ending of Part One, then I still have Part Two and Part Three.
My story opens with 4 weeks left to go of high school. Each chapter titled, 27 days before, 23 days before etc, until The Day. The Day, is where a freak accident kills two students, witnessed by the MC. All Part one builds to this event, with increasing tension. (Which I think of as a climax?).
Then I have Part Two and Part Three, which is where the rest of the story continues, over summer hols and into the beginning of college. Although there's another climax in part three, more towards the end of the novel, though not as catastrophic as the first one.
I guess where your climax is depends on how you tell the story and where (what point in the MC's life) you choose to tell it from... although, the climax from part one doesnt ride out the whole way to the end, the tension varies...