今天 / 明天 / 昨天 / 现在【jīntiān / míngtiān / zuótiān / xiànzài】

A time word such as jīn tiān今天, míng tiān明天, zuó tiān昨天 or xiàn zài现在 goes before the verb: after the subject, or at the very front of the sentence.

English usually puts the time last. In Chinese it never goes after the verb and its object.

• × 我去北京明天 → 我明天去北京
• × 我们见明天下午 → 我们明天下午见

Which position

After the subject is the default. Fronting the time puts weight on it, which is what you want when contrasting one day with another.

When a sentence has both a time and a place, the time comes first.

A full time expression runs from the largest unit down: day, then part of the day, then the hour.

The time word carries the time

qù去 has no tense ending. The same 去 appears in "I go", "I went" and "I'll go", and the time word is what places the event.

The 了 in the second sentence says the coming happened. It is an aspect marker, not a past tense, and a past habit or state takes none: