At what stage / step of development do we start to contemplate on non-self? List below is extracted form Kimattha Sutta noting how skillful virtues lead step-by-step to the consummation of arahantship.  

The question is does skillful virtue require knowledge of non-self or knowledge of non-self is achieved at step 8 when one contemplate on impermanence / conditioned nature of all things including serenity and pleasure one get from virtuous act?


Skillful virtues
freedom from remorse
joy
rapture
serenity
pleasure
concentration
knowledge &amp; vision of things as they actually are
disenchantment
dispassion
knowledge &amp; vision of release
consummation of arahantship
Whatever that is unsatisfactory is not self. Whatever is impermanent is not satisfactory. This is a realisation by direct experience not a form of contemplation. This realisation happens at the stage of "knowledge &amp; vision of things as they actually" which in turn triggers the next stage.