Adding Salt to Cheese
Follow what the recipe calls for.
If your recipe does not state a specific point at which salt should be added to the curds, the general timeline would be to add in the draining phase, when the curds have released most of their whey but are still moist and warm. The warmth of the curds will dissolve the salt efficiently and will absorb salt. Gently toss in the designated amount of kosher or sea salt in 2-3 increments to evenly distribute.
From there, follow the remaining salting procedure (if any) as designated for that style of cheese; i.e. dry-salting or brining. With some styles of cheese, the curds are not salted in the draining process; salt is added in dry salting or brining. This will be clearly stated in the recipe.