  Using Monte Carlo methods, the short-time dynamic scaling behaviour of
two-dimensional critical XY systems is investigated. Our results for the XY
model show that there exists universal scaling behaviour already in the
short-time regime, but the values of the dynamic exponent $z$ differ for
different initial conditions. For the fully frustrated XY model, power law
scaling behaviour is also observed in the short-time regime.
  However, a violation of the standard scaling relation between the exponents
is detected.
