Both "Jiu" (就) and "Cai" (才) are adverbs which relate the verb they modify to a previously specified time or action. Both are often translated as "then". However, "Jiu" implies that the verb it modifies is earlier or sooner than might have been expected, while "Cai" implies that the verb it modifies is later than might have been expected. (Translation hint: the Chinese pattern "Time/Action cai verb" is often expressed by "neg. Verb until Time/Action" in English--don't let the English pattern confuse you.) Practice making distinctions below