Chúng tôi đã hẹn nhau từ tuần trước để cùng đến bữa tiệc này.

Chúng tôi means we, but it is the exclusive kind of we in Vietnamese.

That means the speaker is talking about their group, not including the listener.

So:

• chúng tôi = we (not including you)
• chúng ta = we (including you)

In this sentence, chúng tôi tells us that the speaker and some other people made the plan, but the person being spoken to is not part of that we.

Đã is a marker that often shows something happened in the past or was completed.

In chúng tôi đã hẹn nhau..., it shows that the action of making the arrangement happened earlier.

So:

• đã hẹn = made arrangements / had arranged

Vietnamese does not mark tense the same way English does, so words like đã, đang, and sẽ are often used to give time or aspect clues.

In this sentence, đã works together with từ tuần trước to make the past-time meaning very clear.

Hẹn means to arrange, to make an appointment, or to agree on a meeting.

Nhau adds the idea of each other / one another, so hẹn nhau means:

• to make plans with each other
• to agree together
• to arrange to meet

So this is more natural than just hẹn by itself when the action is mutual between members of the group.

Compare:

• Tôi hẹn bạn = I make an appointment with you / I invite you to meet
• Chúng tôi hẹn nhau = We arranged with each other

Here, nhau emphasizes that the people in chúng tôi made the arrangement mutually.

Từ tuần trước means since last week or from last week.

It highlights the starting point of the arrangement: the plan was made beginning last week.

• tuần trước = last week
• từ tuần trước = from/since last week

In this sentence, từ tuần trước suggests that the arrangement was made as early as last week and has been in place since then.

If you said just tuần trước, that would simply locate the action in last week.
Using từ gives a stronger sense of starting then and continuing up to now.

Để often means in order to, so that, or for the purpose of.

In this sentence:

• đã hẹn nhau từ tuần trước để cùng đến bữa tiệc này
• made arrangements since last week in order to go to this party together

So để connects the arrangement with its purpose.

A simple way to think of it:

• Action 1: hẹn nhau = arrange with each other
• Purpose: để cùng đến bữa tiệc này = so that they could go to this party together

Cùng means together.

So cùng đến means to come/go together.

It shows that the group planned not just to attend the party, but to attend it together.

Some useful comparisons:

• đến bữa tiệc này = come/go to this party
• cùng đến bữa tiệc này = come/go to this party together

The word cùng often appears before a verb to show joint action.

Examples:

• cùng ăn = eat together
• cùng đi = go together
• cùng làm = do together

Yes, đến often means to come, but it can also mean to arrive at / to go to a place or event, depending on context.

In Vietnamese, đến is commonly used with destinations:

• đến trường = go to school / arrive at school
• đến nhà bạn = go to your friend’s house
• đến bữa tiệc = go to the party / come to the party

Whether English translates it as come or go depends on viewpoint. Vietnamese is often less strict than English about that distinction in sentences like this.

So cùng đến bữa tiệc này can naturally mean go to this party together.

Bữa tiệc này means this party.

Breakdown:

• bữa tiệc = party, banquet, celebration meal
• này = this

In Vietnamese, demonstratives like này usually come after the noun, unlike in English.

So:

• English: this party
• Vietnamese: party this → bữa tiệc này

Other examples:

• người này = this person
• cuốn sách này = this book
• ngày này = this day

That word order is very normal in Vietnamese.

Yes, Vietnamese often allows some flexibility with time expressions, but the version here is very natural.

Current order:

• Chúng tôi = subject
• đã hẹn nhau = verb/action
• từ tuần trước = time
• để cùng đến bữa tiệc này = purpose

This is a very common pattern: Subject + đã + verb + time + để + purpose

You could also hear variations depending on emphasis, such as putting the time expression earlier, but the sentence as given sounds smooth and standard.

For learners, it is useful to understand the structure as:

We + had arranged + since last week + in order to + go together to this party.

Yes, hẹn gặp nhau is possible, but it is slightly more explicit.

• hẹn nhau = arrange with each other / make plans together
• hẹn gặp nhau = arrange to meet each other

In this sentence, hẹn nhau already works well because the context makes the plan clear: they arranged ahead of time to go to the party together.

If you said:

• Chúng tôi đã hẹn gặp nhau từ tuần trước...

that would place a bit more emphasis on the idea of actually meeting each other.
The original sentence sounds more natural and less heavy.

Not always strictly necessary, but it is very natural here.

Since từ tuần trước already tells us the arrangement started last week, the past meaning is understandable even without đã. However, adding đã makes the sentence clearer and more complete in standard usage.

Compare:

• Chúng tôi hẹn nhau từ tuần trước...
  understandable, but less explicitly marked
• Chúng tôi đã hẹn nhau từ tuần trước...
  clearly marked as a completed prior arrangement

Vietnamese often relies on context, so not every tense marker is required all the time. But in this sentence, đã sounds very appropriate.

It can refer to two or more people.

So chúng tôi does not require a large group. It simply means we excluding the listener.

For example, it could mean:

• the speaker and one friend
• the speaker and several friends
• the speaker and colleagues

The exact number is not specified.

A helpful breakdown is:

• Chúng tôi = we
• đã hẹn nhau = had arranged with each other
• từ tuần trước = since last week
• để = in order to / so that
• cùng đến = go/come together
• bữa tiệc này = this party

So the structure is:

Subject + past marker + mutual arrangement + time expression + purpose clause

This is a very typical Vietnamese sentence pattern and a good example of how Vietnamese uses:

• pronouns carefully
• aspect markers like đã
• reciprocal nhau
• post-noun demonstratives like này
• purpose marker để