Here's what I do, which is based on reading this forum for over four months, especially reading posts by the long-time users:
When the atty is new or empty, drip in five drops, blow lightly to push the
juice down into the ceramic bowl, and then add three more drops. It's ready to
vape after you let it sit for a minute or so (so the
juice can soak into the bottom of the atty). After about 9 drags, drip in three more drops. Keep repeating the last step after about 9 drags or when you notice the flavor is getting less or when there's a slight burnt taste (don't inhale when that happens). Three drops is about nine drags (depending on how long your drags last) or similar to one cigarette.