Mislim da ćemo stići na vrijeme.

In Croatian, da often introduces a subordinate clause, especially after verbs like mislim (I think), znam (I know), nadam se (I hope), and similar expressions.

So:

• Mislim da ćemo stići na vrijeme. = I think that we will arrive on time.

This da is very often the equivalent of English that in this kind of sentence. Just like in English, it can sound optional in translation, but in Croatian it is normally included here.

Ćemo is the 1st person plural form of the future auxiliary, meaning we will.

It comes from the verb htjeti (to want), which is also used to form the future tense.

Here is the pattern:

• ja ću = I will
• ti ćeš = you will
• on/ona/ono će = he/she/it will
• mi ćemo = we will
• vi ćete = you will
• oni/one/ona će = they will

So in your sentence:

• ćemo stići = we will arrive

Croatian future tense is usually formed with:

• the auxiliary ću, ćeš, će, ćemo, ćete, će
• plus the infinitive of the main verb

So:

• ćemo stići = we will arrive
• literally something like we-will arrive

The verb stići stays in the infinitive, while ćemo carries the person and number.

This is because ćemo is a clitic. In Croatian, clitics usually go in the second position of their clause.

In the clause:

• da ćemo stići na vrijeme

the first element is da, so the clitic ćemo comes right after it.

That is why da ćemo stići sounds natural, while da stići ćemo is not standard word order.

This is a very important Croatian pattern:

• Mislim da ćemo...
• Znam da će...
• Nadam se da ćete...

Croatian often leaves out subject pronouns when they are already clear from the verb form.

Here, ćemo already tells you the subject is we.

So Croatian does not need an explicit mi:

• Mislim da ćemo stići na vrijeme. = normal, natural
• Mislim da mi ćemo stići na vrijeme. = not natural in standard word order

If you want to add emphasis, Croatian can use mi, but it must be placed correctly:

• Mislim da ćemo mi stići na vrijeme. = I think that we will arrive on time (with emphasis on we)

Stići means to arrive, to reach, or sometimes to make it in time / manage to get there depending on context.

In this sentence, it means:

• to arrive
• or more naturally, to make it

So:

• Mislim da ćemo stići na vrijeme. can feel like
  • I think we’ll arrive on time
  • I think we’ll make it on time

This verb is very common when talking about getting somewhere before a deadline or expected time.

Both stići and doći can relate to arriving, but they are not always used in exactly the same way.

• doći = to come / to arrive
• stići = to arrive / to reach / to make it, often with a sense of reaching a place or moment successfully

With na vrijeme (on time), stići is especially natural because it often implies successfully getting there in time.

So:

• stići na vrijeme = a very common combination

A learner will hear this often.

Na vrijeme is a fixed Croatian expression meaning on time.

Here, na is followed by the accusative case. The noun is vrijeme (time), and in this noun the nominative and accusative singular look the same:

• nominative: vrijeme
• accusative: vrijeme

So even though the form does not change, this is functioning as accusative after na in this expression.

It is best to learn na vrijeme as a whole phrase:

• na vrijeme = on time
• u vrijeme does not mean the same thing here

Usually, na vrijeme is taught as on time. In many real situations, it can also overlap with English in time, depending on context.

For example:

• Stigli smo na vrijeme. could mean We arrived on time or We made it in time.

So the Croatian phrase covers the idea of arriving by the needed or expected time. English may choose on time or in time depending on the situation.

Stići is a perfective verb.

In Croatian, aspect matters a lot. Perfective verbs usually describe an action as a completed whole or a single achieved result.

That fits this sentence well, because arriving is seen as a completed event:

• stići = to arrive, to reach, to make it

Its imperfective partner is often stizati, which describes repeated, ongoing, or habitual arriving.

Compare:

• Mislim da ćemo stići na vrijeme. = I think we’ll arrive / make it on time.
  (one completed future event)

• Stižemo rano svaki dan. = We arrive early every day.
  (habitual/repeated action)

For a single future arrival, stići is the natural choice.

A few pronunciation points are useful here:

• ć is a soft sound, somewhat similar to a very soft ch/t sound
• č is harder than ć
• English speakers often find this distinction difficult at first

Approximate pronunciation:

• ćemo ≈ TYEH-mo with a soft ty/ch sound
• stići ≈ STEE-chee, but with that same soft ć sound, not a hard English ch

Also:

• lj, nj, j, č, ć, š, ž are all worth learning carefully in Croatian because they can change meaning.

You do not need perfect pronunciation immediately, but it is good to notice that ć and č are different letters.

Yes, Croatian word order is somewhat flexible, but not completely free. In this sentence, the most important restriction is that the clitic ćemo must stay in a normal clitic position.

The standard sentence is:

• Mislim da ćemo stići na vrijeme.

You may also hear variations for emphasis, such as:

• Mislim da ćemo na vrijeme stići.

That can sound more marked or stylistic.

But:

• Mislim da stići ćemo na vrijeme.

is not standard.

So yes, some movement is possible, but the placement of ćemo is heavily constrained.

In this sentence, normally no. Croatian generally keeps da after mislim when introducing a full clause.

English can say:

• I think we’ll arrive on time.

Croatian normally says:

• Mislim da ćemo stići na vrijeme.

Leaving out da here would sound wrong or at least highly non-standard.

So this is one of those places where English and Croatian differ:

• English often drops that
• Croatian usually keeps da

Mislim most commonly means I think, but depending on context it can also mean:

• I believe
• I suppose
• I mean / I have in mind
• I am thinking about

In your sentence, it clearly means I think in the sense of expressing an opinion or expectation:

• Mislim da ćemo stići na vrijeme. = I think we’ll arrive on time.

So here it introduces a judgment or prediction, not a literal process of thinking about something.

Yes, it sounds completely natural and everyday.

It is a very typical Croatian structure:

• Mislim da... = I think that...
• ćemo + infinitive = we will ...
• na vrijeme = on time

So this is exactly the kind of sentence a learner should know and reuse with other verbs, for example:

• Mislim da ćemo uspjeti. = I think we’ll succeed.
• Mislim da ćemo doći rano. = I think we’ll come early.
• Mislim da ćemo završiti danas. = I think we’ll finish today.