  We study the early time behavior of the Baxter-Wu model, an Ising model with
three-spin interactions on a triangular lattice. Our estimates for the dynamic
exponent $z$ are compatible with results recently obtained for two models which
belong to the same universality class of the Baxter-Wu model: the
two-dimensional four-state Potts model and the Ising model with three-spin
interactions in one direction. However, our estimates for the dynamic exponent
$\theta $ of the Baxter-Wu model are completely different from the values
obtained for those models. This discrepancy could be related to the absence of
a marginal operator in the Baxter-Wu model.
