But as you yourself agreed, she's been scouting for the best matchups. IF she has any flexibility in assigning fights — yes, that's a big "if" — she's not going to dump the MC into directly going against the best fighter there. There also will be a certain degree of luck to things. Depending on what system they use for competing, the actual #1 and #2 fighters (by skill level) could always face each other very early on. If they use a standard sports bracketing system, probably not, but who knows what they use? They could always pick balls out of a jar or something.
From what's been shown so far, the MC seems to be an extremely quick learner generally. Depending on his natural talent level, it's conceivable that he corrects flaws very quickly and doesn't need a lot of handholding. If Cap doesn't have to spend too much time fixing problems — because the MC corrects them immediately and doesn't make the mistakes again — there would be a decent amount of time learning new things instead of focusing so much on errors. And during the first experience seeing the MC demonstrate his fighting, Cap seemed to feel like the MC had potential. That says that at least some things the MC did were in the ballpark of correct. (That doesn't mean they don't need work, even a lot of it, of course.)
And again, we're assuming that every episode is a week. That seems right, but if we're wrong, there could be even more practice time under the MC's belt. Either way, it's not like the competition is the day after seeing the fighters, so there's still time. Erika even made it sound like he'll have sufficient time to practice with Cap.