Big Picture,
I can't think of a Classic Trainer with a Seniority Number before 1 Jan 2000, so none will have seniority to hold a pax command.
Back on topic, for those thinking of joining CX on the freighter and grabbing a quick command the emperical evidence would suggest it happens very rarely. For those completely new to CX, the quickest I have seen it done is about 18 months and even then the number of successful candidates can be counted on one hand!!
Whilst not disputing the claim in the advertisement is technically true, it is a sales pitch, and as such needs to viewed in that light.............