An entire stick in one go is too much. Depending on how big that stick is, of course.
You want enough to cover the entire board, and so that there is minimal iron>board contact. Your iron should be gliding on the wax and warming the base at the same time to get the wax in.
That said, you can never use too much wax (if its dripping off the sides, you're probably using too much actually), but if you don't use enough, you run the risk of damaging your base.
I just got a wax and tuning kit recently, so I've been reading up on it like its my job.