Has anyone back-calculated previous close encounters between the Apophis asteroid and Earth?
The JPL Small Body Database lists Apophis close approaches dating back 100 years before discovery.
Three fairly close ones were:

1907-04-13, 0.029 au
1949-04-14, 0.028 au
1990-04-14, 0.033 au

While it's possible to run a dynamical integrator arbitrarily far backward or forward in time, any given pos(t), vel(t) state is only a point in a cloud of possibilities.
Observations (MPC database, NASA news) constrain that cloud; close encounters accelerate its dispersion.
Specific predictions before ~1900 or after ~2050 should not be regarded with much confidence.