hey guys i just started my first home-made wine!!

cuz we live in a country where alcohol is prohibited so i followed a recipe
3 litres grape juice
2 litres water
1 cup of sugar
brewery yeast (cuz we dont have wine yeast)
and a balloon air lock
this is the 3rd day and the fermentation is still going but
not too crazy and there is no foaming, so is there something wrong and how could i know that the primary fermentation is done (i just bought a hydrometer)?
thank you in advance for your help