The feeling that one is constantly one step away from enlightenment: does it have a Buddhist term for it? Pejorative or otherwise.
So I've heard of beginner's mind, but I doubt it covers it.
That feeling correlates to different mental states. For instance, if you believe yourself to be privileged because you (unlike others) are only one step away from enlightenment, then the basic affiliated mind is one of 'pride'.
However, if it stems from your aspiration to enlightenment, and your aspiration itself is rooted in renunciation where you - having recognised the universal pervasion of the three marks of existence - are thereby determined to make use of every moment of your entire being to achieve liberation (and, in the Mahayana, all beings) then that feeling is of great benefit, and is a mark of 'effort'. The 'three efforts' in Mahayana (not disparate from Right Effort in the eightfold path) are: