就 vs 才: early/easy vs late/hard
副词 / adverbs (时间)
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Time / Quantity + 就 + V + 了 / Time / Quantity + 才 + V
These two adverbs add the speaker's judgement about a time or amount:
就 = earlier / faster / easier than expected. Usually with 了: 我八点就到了 (I was there by 8, early!).
才 = later / slower / harder than expected. No 了: 他十点才到 (he didn't arrive until 10, late!).
With an amount, 才 can also mean "only": 这件衣服才五十块 (this top is only 50 yuan).
Examples
我昨天下单，今天就到了。
Wǒ zuótiān xiàdān, jīntiān jiù dào le.I ordered yesterday and it's already arrived today.
快递一个星期才到。
Kuàidì yí ge xīngqī cái dào.The parcel took a whole week to arrive.
他十一点才起床。
Tā shíyī diǎn cái qǐchuáng.He didn't get up until eleven.
这双鞋才一百块，太便宜了！
Zhè shuāng xié cái yìbǎi kuài, tài piányi le!These shoes are only 100 yuan, what a bargain!
Common mistakes
✗ 他十点才到了 → ✓ 他十点才到 (no 了 with 才).
✗ 才他十点到 → ✓ 他十点才到 (才 before the verb).