Hole self-localization into polaron states is a phenomenon characteristic of many wide bandgap compounds including transparent semiconducting oxide beta-Ga2O3. While this effect has been recognized for some time, its dynamics remained elusive, and self-localization has often been considered instantaneous. In this work, using the two-color ultrafast pump-probe technique, we have measured the hole self-localization time in beta-Ga2O3. At room temperature, this time has been found to be 0.5 ps increasing to 1.1 ps at 10K. In terms of the configuration coordinate diagram, at room temperature, tunneling and thermal activation contribute to the process with similar weights. The hole self-trapping coefficient is estimated to be 6.4x10(-8)cm(3)/s.