Is the original oil special

Paramagnetic metals have a small and positive susceptibility to magnetic fields. These materials are slightly attracted by a magnetic field and the material does not retain the magnetic properties when the external field is removed. Paramagnetic properties are due to the presence of some unpaired electrons, and from the realignment of the electron orbits caused by the external magnetic field. Paramagnetic materials include magnesium, molybdenum, lithium, and tantalum. [Source]

You can change your oil whenever you want. It's fine to go synthetic at the first change.

Yes, the oil in the Prius from the factory is special - it's the first oil your new Prius has seen! (It's just regular oil, in case you didn't get my sense of humor.)