'최근 데뷔 6개월 차에 ...' => Recently going on/into their sixth month since debut ... 차 is what we call 의존명사 (dependent noun, or bound noun) which requires a qualifying phrase before it. It has a few different meanings. 1) number of occurrences, like "N-th" = 째, 번, 번째. "제2 차 세계대전" (The Second World War). 2) a moment or occasion to do something = 때, 순간. "막 떠나려던 차였어" (I was just about to leave). 3) number of cycles (month, year, etc) expressing a duration = 째. "그는 입사 3년 차다" (He's in the third year of working here). As you guessed, your example has the (3) meaning. It can be interpreted as 최근에 데뷔 6개월을 [or 6개월 째를] 맞아서 최근 refers to the time point of the sixth month since the debut, not the debut itself.