I have younger GEO colleagues who have not previously been KPs. I've not really asked but think they're around GEO3/4. Also haven't asked if they're scholars, but I don't think so (possibly teaching award holders, though from what I've heard I don't think those are especially fast-tracked).

I *think* your CEP needs to be at SEO1 level, but you don't necessarily need to there yet (I applied in as GEO as well) or have held KP appointment. Unfortunately CEP is not known to officers so it might be difficult to gauge eligibility.

Ultimately, if you are interested in a particular role, it probably won't hurt to apply. Having held a KP position would help, but the main challenge is really to convince interviewers (also prospective bosses/supervisors) that you have the skillset for the job, ideally supported by your previous work experiences.