For how long does it take for a wine slushy to freeze?

Assuming you mean in a standard kitchen freezer:

It will take around 2 hours for your red wine slushy to freeze strong. If you desire it to be the ideal consistency, we suggest examining it every 45 minutes or so to provide it a stir. This will assist to avoid large ice crystals from forming and destroying the smooth, slushy texture. you could check here