In English, 才 (cái) might be expressed with “as late as” or “not until.”  We often use the 才 (cái) pattern with a time of some sort, like a specific time of day, age, etc. Moreover, this pattern is essentially the opposite of using 就 (jiù) to express earliness. 就 means something happened earlier than expected. Remember to distinguish these two words so you won’t mix them up.