You can use mwsmith's bleach calculator to figure out how much bleach you need to add at a time to maintain your minimum chlorine level. If you'll test daily, it won't take you long to begin to anticipate how much/when your pool uses it up.

When I add the bleach to my pool, I never pour it into the skimmer--I pour it slowly into the stream from my return, and let it mix that way.

Janet