Maximizing premerger warning times in gravitational-wave searches requires minimizing algorithmic latency. While current pipelines typically rely on truncated linear-phase filters, minimum-phase whitening offers a zero-latency alternative that eliminates the acausal look-ahead buffer. However, this causal approach exposes the analysis to “spectral drift,” where the whitening operator applied to live data diverges from the static template bank, creating a functional perturbation of the matched-filter metric. We develop a perturbative framework generalizing the Cutler-Vallisneri formalism to address these metric errors, deriving analytic expressions for the resulting timing, phase, and SNR biases. Validated against exact stationary-phase models and numerical injections, the corrections achieve $<1\%$ fractional error at typical catalog drift amplitudes ($\epsilon \sim 0.1$), remaining controlled out to $\epsilon \lesssim 0.5$. Applied to GWTC-4.0 events under realistic 1-wk power spectral density lags, the framework reveals uncorrected timing biases exceeding $200\mathrm{\mu s}$, phase shifts up to 0.2 rad, sky-localization centroid shifts of 5°–10° in a timing-only triangulation model and a median SNR loss of 3%–5% ($\sim 15\%$ reduction in detection volume). These results demonstrate that while minimum-phase whitening maximizes the early-warning window, analytic drift corrections are essential to maintain detection sensitivity in future observing runs.

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• General relativity formalism
• Gravitational wave detection
• Gravitational waves