The system and method for accurately determining range-to-go for a time-delayed command detonation of a projectile. Using dual laser and/or radio frequency detectors on the tail and on the nose of a spinning projectile to determine the range-to-go, time-to-go, and/or lateral offset from the projectile to the target. A time to detonation clock is used to determine when a projectile transitions from an exterior to an interior of a structure such that the projectile can more accurately detonate within a fixed structure.