How can you consistently separate Kefir into curds and whey for cheesemaking?
With milk kefir, if you over-ferment it, you will see it break into at least two if not three layers. Slightly cloudy whey is one of them. Without that, you can strain out some grains, but getting a curd is going to be difficult. You can try  acidifying the kefir with lemon juice or vinegar to coax out a curd, but it would be much easier if you let it over-ferment. That means patience (many days) if you have a cool ambient temperature or you can somehow keep it warm (say 30C) for a day. The type of milk matters too. Homogenised fresh milk tends to be harder to work with, and UHT tends to be easier.

You need to see a distinct layer of whey first before trying. It should not take more than half a day to strain out the curd. Salting the over-fermented kefir before straining also helps.