I would say that neither the Sorcerer nor the Wizard automatically start with a Familiar.
The PHB says they "can obtain a familiar." The procedure is then given for doing so. It does not say that either class begins with one, whereas the Druid specifically states that they can begin play with an Animal Companion.
I don't think it would make a large difference if a Wizard or Sorcerer did start play with one, but by the rules they wouldn't.