Just to add a bit to this:
In addition to the remnant magnetization issue that Matt mentioned, where you close the circuit on startup will also alter inrush. The V=Ldi/dt (Voltage across an inductor is equal to the inductance times the rate change in current over time) that causes the 90 degree phase shift in the steady state (after everything has settled down) is also active from the very beginning.
A slightly different way to think about that di/dt term is to instead think of the 'volt-second' product. If you apply X volts for T seconds to an inductor, then the magnetic flux and its associated current flow will change by a given amount. The key here is that the volt-second product does not determine how much flux the transformer is carrying; it determines the _change_ in the amount of flux that the transformer is carrying.
When you apply AC voltage to a transformer, than the maximum change in magnetic flux is cause by a whole half cycle. In the steady state case, when the _positive_ voltage half cycle starts, the magnet flux is maximum in the negative direction. By the end of the positive half cycle, the magnetic flux is maximum in the positive direction; thus you have a change from -max to +max. Note that this is the 90 degree phase shift that Matt mentions.
Now imagine that you have a perfect transformer core, with _zero_ remnant magnetization. Close the circuit on this core just at the point where the positive half cycle starts. Since the magnetic flux is starting at zero, and a given half cycle results in a specific _change_ in magnetic flux, then by the end of this first half cycle, the magnetic flux needs to be _twice_ the normal steady state maximum.
A real transformer won't reach this double flux state, but instead will saturate the core. In trying to get to this double flux state, quite a bit of current will flow, since a saturated core takes more current to get a change in flux level. If you want to minimize the inrush current, then you not only want to open the circuit at the peak voltage point, you also want to close the circuit at the peak voltage point.
-Jon