Onda ću doći.

Ću is the 1st person singular future auxiliary, from the verb hteti (to want), but here it functions like will in English.

So:

• ću = I will
• doći = come / arrive

Together, ću doći means I will come.

In Serbian, the subject pronoun is often left out because the verb already shows the person.

Here, ću already tells you the subject is I.

So:

• Ja ću doći. = I will come.
• Ću doći. would sound incomplete on its own
• Onda ću doći. is fine because ću already marks I

You can add ja for emphasis:

• Ja ću doći. = I will come.

Because ću is a clitic. In Serbian, clitics usually go near the second position in the sentence.

So in:

• Onda ću doći.

the first element is onda, and the clitic ću comes right after it.

This is very normal Serbian word order.

Compare:

• Ja ću doći.
• Sutra ću doći.
• Onda ću doći.

In each case, the clitic comes after the first word or phrase.

Onda usually means then.

In a sentence like this, it can mean:

• then in time: at that point
• then in logic: in that case

So depending on context, Onda ću doći could mean something like:

• Then I’ll come.
• In that case, I’ll come.

The exact nuance comes from the situation, not from the sentence alone.

Because after ću, standard Serbian normally uses the infinitive.

So:

• ću doći = I will come

Here:

• doći = infinitive (to come / to arrive)

By contrast, dođem is a present-tense form used in other constructions, for example:

• Hoću da dođem. = I want to come.
• Kad dođem... = When I come...

So in this sentence, doći is the correct form.

Yes. In modern spoken Serbian, ću da + present tense is very common:

• Onda ću da dođem.

This means the same thing as:

• Onda ću doći.

A useful rough distinction:

• ću doći = very standard, concise, neutral
• ću da dođem = also very common, especially in speech

Both are correct and natural in many contexts.

Yes. Doći is perfective, while dolaziti is imperfective.

That matters because Serbian verbs often come in aspect pairs.

• doći = to come / arrive as a completed event
• dolaziti = to be coming / to come repeatedly / habitually

So:

• Onda ću doći. suggests one completed arrival: Then I’ll come / arrive.

If you used dolaziti, the meaning would be different, more like repeated or ongoing coming, depending on context.

For a simple one-time future event, doći is the natural choice.

Yes, but the emphasis can change.

For example:

• Onda ću doći.
• Ja ću onda doći.
• Doći ću onda.

All of these can be possible, depending on context.

However:

• Onda ću doći. sounds very natural if you are emphasizing then
• Ja ću onda doći. can emphasize I
• Doći ću onda. can sound more marked, depending on context

Serbian word order is more flexible than English, but it is not random. Clitics like ću still follow special placement rules.

A simple approximation:

• Onda ≈ OHN-da
• ću ≈ something like tyoo, with a very soft t/ch sound
• doći ≈ roughly DOH-ći, again with that soft ć

The sound ć does not exactly exist in English. It is softer than English ch.

So:

• ću is not like a hard choo
• doći is not exactly do-chee, though that approximation can help at first

If you already know č and ć, remember that ć is the softer one.

You would use neću:

• Onda neću doći. = Then I won’t come.

Here:

• ću = I will
• neću = I will not

This negative form is very common and should be learned as a whole form.

Yes. Doći often means both come and arrive, depending on context.

So Onda ću doći could be understood as:

• Then I’ll come
• Then I’ll arrive

English often separates those ideas more clearly than Serbian does. Serbian doći can cover both.