For how long does it consider a wine slushy to freeze?

Presuming you mean in a standard kitchen area freezer:

It will take around 2 hours for your wine slushy to freeze solid.  https://zerogov.net/?p=1251 However, if you want it to be the best consistency, we recommend checking it every 45 minutes or so to offer it a stir. This will help to prevent large ice crystals from forming and messing up the smooth, slushy texture. visit