I’m actually just waking up some milk grains myself, and they were already hydrated, so I’m not the best person to ask about dairy kefir. Dom says they’re ready if it coagulates within 24-hours. If this is happening, why not leave it for 36-48 hours and then taste it? You could ripen for 12-24-hours too. If it’s tangy, fizzy, sour etc it should be fine. Even a 24-hour fermented one is likely to have less lactose/more CFUs than commercial ones. Have you noticed any grain growth at all?