You can renew your CFI by giving the FAA your instructor pilot Form 8. The Form 8 has to be within 12 months of the time you apply for your CFI renewal. With the AF on a 17 month checkride cycle, the CFI ticket expiring after 24 months, and you being allowed to renew your CFI up to 12 months from your IP checkride, there's an opportunity to be SOL for a CFI renewal even if your AF IP Form 8 is current...manage when you renew accordingly. Check out 61.197(b)(2)(iv) for the details.