To compare Mandarin and Cantonese in 2 case: Cantonese: 你 幾時 生日呀？ same as Mandarin: 你 甚麼時候 生日 呢？ Direct explain(wrong grammar): You when birthday ? You can also say: Mandarin: 你 生日 是 甚麼時候呢？ Same as Cantonese: 你生日 喺 幾時呀？ Direct explain(wrong grammar): Your birthday is when? The part of speech is corresponding!! One more example: Mandarin: 甚麼時候 是 你生日 呢？ Cantonese: 幾時 喺 你生日 呀？ Direct explain(wrong grammar): When is your birthday? In Chinese, they are all right, but it depends on how to arrange the part of speech. Th reason is that the main point in a sentence is different . Normally, it will strengthen the words according to the sound, stress and pause. It is an another question. In basically, the word order have different arrangements according your personal feelings or habits. However, one thing, that I am not sure, is all Mandarin sentence can correspond to Cantonese sentence. At least in this case can be corresponding to these them. Hopefully it can help you.

To compare Mandarin and Cantonese in 2 case: Cantonese: 你 幾時 生日呀？ same as Mandarin: 你 甚麼時候 生日 呢？ Direct explain(wrong grammar): You when birthday ? You can also say: Mandarin: 你 生日 是 甚麼時候呢？ Same as Cantonese: 你生日 喺 幾時呀？ Direct explain(wrong grammar): Your birthday is when? The part of speech is corresponding!!

Thank you so much, jashiroko. *When you type in Cantonese, which input method do you use? 倉頡? 粵拼? Because I don't know how to type in Cantonese so I just type out the words using Mandarin pinyin. xD

Yes, in this case 幾時 comes before 生日. I’m not a teacher, but as a native speaker, I can confirm you that it’s always the case with 幾時 (when) e.g. 你幾時食飯呀？你幾時返屋企？ That’s an incredibly common way to ask about When things happen. But, you can also hear Cantonese speakers say - in a manner closer to Mandarin: 你生日係幾時？ In this case you only swap 是 to 係, then you’re speaking perfect Cantonese and expressing the same meaning. To sum up, Cantonese might just have more flexible grammar/order when asking about when.