I've never heard Vincentia used. It would be Vincenza, which is used but not so much because is generally considered very ugly. There's also the nickname Enza as a possiblity (another name that's generally considered ugly). Victoria seems a stretch, and anyway the Italian form of Victoria is Vittoria.
Btw, Vincentio isn't used either, it's always Vincenzo. Shakespeare's Italian names are often a little weird, at least for modern standards.