Which is Dress Up Night on Wonder?

[Uno Mas]

From looking at the most recent Navigator, it looks like Monday (Nassau day) is dress up night on the Wonder. Anyone know if that's consistently the night on the 4-night Wonder cruise, or can it change? That's my Palo night and it would be great to only have to pack one fancy outfit if they coincided - but I'm not sure I want to take the chance if the dressy night could potentially fall on a different night. We leave this Sunday!