When you say "triggered," do you mean the initial presentation of ITP? I think many on here have no idea when they first developed ITP, because they weren't already getting regular CBCs. Many, like my daughter, develop sudden bruising or petchiae, and learn they have a low platelet count. In her case, we could only find one prior count, done for a medical procedure earlier that year. She'd been so healthy, we had skipped the CBC for the annual school sport physical because she was needle-shy. If you mean going from a safe count to terribly low, once she was getting regular CBCs, we could count on seeing a lower number almost immediately if she developed a cold virus. Some others on here have said their counts actually rose in response to illness. It's probably too wildly varied to count on anyone else's experience. I tried keeping a chart for the first year, but the numbers were really all over the place, with little correlation to anything.
