  Since gravitational and electromagnetic waves from a compact binary
coalescence carry independent information about the source, the joint
observation is important for understanding the physical mechanisms of the
emissions. Rapid detection and source localization of a gravitational wave
signal are crucial for the joint observation to be successful. For a signal
with a high signal-to-noise ratio, it is even possible to detect it before the
merger, which is called early warning. In this letter, we estimate the
performances of the early warning for neutron-star black-hole binaries,
considering the precession effect of a binary orbit, with the near-future
detectors such as A+, AdV+, KAGRA+, and Voyager. We find that a gravitational
wave source can be localized in $100 \,\mathrm{deg^2}$ on the sky before $\sim
10$--$40 \,\mathrm{s}$ of time to merger once per year.
