  The Laser Interferometer Gravitational wave Observatory (LIGO) and Virgo,
advanced ground-based gravitational-wave detectors, will begin collecting
science data in 2015. With first detections expected to follow, it is important
to quantify how well generic gravitational-wave transients can be localized on
the sky. This is crucial for correctly identifying electromagnetic counterparts
as well as understanding gravitational-wave physics and source populations. We
present a study of sky localization capabilities for two search and parameter
estimation algorithms: \emph{coherent WaveBurst}, a constrained likelihood
algorithm operating in close to real-time, and \emph{LALInferenceBurst}, a
Markov chain Monte Carlo parameter estimation algorithm developed to recover
generic transient signals with latency of a few hours. Furthermore, we focus on
the first few years of the advanced detector era, when we expect to only have
two (2015) and later three (2016) operational detectors, all below design
sensitivity. These detector configurations can produce significantly different
sky localizations, which we quantify in detail. We observe a clear improvement
in localization of the average detected signal when progressing from
two-detector to three-detector networks, as expected. Although localization
depends on the waveform morphology, approximately 50% of detected signals would
be imaged after observing 100-200 deg$^2$ in 2015 and 60-110 deg$^2$ in 2016,
although knowledge of the waveform can reduce this to as little as 22 deg$^2$.
This is the first comprehensive study on sky localization capabilities for
generic transients of the early network of advanced LIGO and Virgo detectors,
including the early LIGO-only two-detector configuration.
