才 is the long blank stretch before you arrive

Where the picture shows up in 才

1. 1

   a long blank on the clock

   他八点才来。

   tā bā diǎn cái lái

   He did not show up until eight.

2. 2

   waiting as the blank

   我等了一个小时才见到医生。

   wǒ děng le yí ge xiǎoshí cái jiàn dào yīshēng

   I waited an hour before I finally saw the doctor.

3. 3

   a condition as the blank

   只有你来了我才放心。

   zhǐyǒu nǐ lái le wǒ cái fàngxīn

   I will not relax until you are here.

4. 4

   what turns up after the wrong turns

   这才是重点。

   zhè cái shì zhòngdiǎn

   This is the real point.

5. 5

   falling short of the mark

   他才十六岁。

   tā cái shíliù suì

   He is only sixteen.

   才 rarely takes 了 after it. 他八点才来了 sounds wrong; 他八点才来 is what people say.