Hello Kenneth,
Before I give you my answer, just a quick point of clarification: Because you have not yet passed your exam, you need to show 35 Contact Hours and not PDUs. PDUs are only needed after you actually pass your exam. But frankly, that's really more of a semantic detail and doesn't change the answer.
Because the answer is: Never.
The certificate for 35 contact hours that you received from us never expires. PMI clearly states this in their handbook by saying the following:
"Verify at least 35 contact hours of specific instruction that addressed learning objectives in project management. R eco rd al l education hours regardless of when they were accrued"
