Both  (cái) and  (jiù) are adverbs that have to do with expressing time, and they are both placed in front of the verb. However, they have opposite effects on the tone of the sentence, with  (cái) implying a=the speaker's sense of lateness, and  (jiù) imparting a sense of earliness.

Emphasis with 

Expressing Lateness with "cái"

才 indicates that the speaker feels that the events discussed happened later than expected. Sometimes it also expresses anxiety, impatience, anger, or other related emotions.

Structure

Subj. + Time Word +  + Verb

Examples

Expressing Small Quantity with "cái"

 can also mean "only" in the sense of a small quantity.

Structure

 ( + Verb) + Measure Word + Noun

Examples

Expressing earliness with "cai"

"才"表示动作在说话前不久发生,有" 刚、刚刚"的意思。常常跟"就"连用,形容某事发生得很快。

Structure

Subj. +  + Verb


(现在) +  + Time

Examples

Emphasis with 

Used to Express Earliness

就 indicates that something has occurred earlier than the speaker expected. There may be an accompanying feeling of surprise or amazement.

Structure

Subj. + Time +  + Verb + Obj.+

Examples

Used to Express Small Quantity

 can be used to mean "only," in the sense of a small quantity.

Structure

Subj. +  + (+Verb) + Measure Word + Noun

Examples

See also

Sources and further reading

Books