This manga makes no sense, It contradicts what it starts with, that being Saint Knight is a never before seen hidden class. Then they say its a support class, which it obviously isn't, and how would you know that since its the first of its kind? And there's also the time skips between chapters that makes it confusing.
The skips between chapters can be a bit jarring, I agree, but where does it say Saint Knight is a never before seen hidden class? Best I can see is a student saying they've never seen them before, which makes sense if hidden classes are as rare as implied. The teacher, however, immediately identifies them as hidden classes and the first university rep's offer including 3 skill books exclusive to Saint Knight, implying the class HAS been seen before but is simply very rare.
That 1 student's comment is the only evidence for your claim while the rest debunks it and implies that student simply hadn't seen them before.
That said, at least up to where I am, it hasn't explained how MC knew all about all 3 classes unless either he somehow knew of them or the class selection thing or system gave him a basic understanding. Seems to be skipping over some very needed explanations and world building so far.