"They have dinner at 8 on Saturdays."

Translation: 他们星期六八点吃晚饭。

[Mar_ty]

Would it be really incorrect to write: 他们八点星期六吃晚饭 ?

[RuhRoh1]

Yes because in Chinese, when speaking of time you always go from largest to smallest. At least from what I know. I'm not a native speaker.

[ShannAwesome]

Yes, time adjectives go from largest to smallest. You would put year, month, date, time in that order if you were using them all in one sentence.

[JustinCAquino]

It's understandable but does not follow proper form: big dates like years, months, weeks to small draws like days of the week, time of day and exact time.