Stižem ujutro.

Because Serbian usually leaves out subject pronouns when the verb ending already makes the subject clear.

In stižem, the ending -em tells you it is first person singular, so ja is understood automatically.

You can add ja only if you want emphasis or contrast, for example:

Ja stižem ujutro, a on uveče.
= I’m arriving in the morning, and he in the evening.

Grammatically, stižem is present tense.

However, Serbian often uses the present tense of an imperfective verb for a planned or expected future action, especially when there is a time expression like ujutro.

So this sentence can naturally refer to a future arrival, even though the verb form is present.

If you want a more explicitly future form, you could say:

Stići ću ujutro.

The dictionary form is stizati, which is the imperfective verb.

Its perfective partner is stići.

This matters because Serbian often chooses between imperfective and perfective depending on how the action is viewed:

• stizati / stižem = arriving, being on the way to arrival, scheduled arrival, repeated arrival
• stići = to arrive, to reach, viewed as a completed event

In this sentence, stižem sounds natural because Serbian commonly uses the imperfective present for a planned future action.

Because stignem is the present form of the perfective verb stići, and that is not the usual choice for a simple sentence like this.

For a statement such as I’m arriving in the morning, Serbian normally prefers:

• Stižem ujutro. for a planned/arranged arrival
• Stići ću ujutro. for an explicit future

You will often see stignem in clauses like:

Kad stignem, javiću se.
= When I arrive, I’ll let you know.

So stignem is a real form, but not the most natural one for this exact sentence.

Both can be translated with something like I’m coming / I’m arriving, but they are not exactly the same.

• dolazim focuses more on coming
• stižem focuses more on arriving / reaching the destination

So:

• Dolazim ujutro = I’m coming in the morning
• Stižem ujutro = I’m arriving in the morning

In many situations, both are possible, but stižem often sounds a bit more like I get there in the morning.

Yes. Ujutro is a fixed adverb meaning in the morning, so learners should usually treat it as one whole word.

You may also hear and see ujutru. Both are used, and both are understood. In Serbian, ujutru is very common, while ujutro is also widely used and fully understandable.

So these are both fine:

• Stižem ujutro.
• Stižem ujutru.

For this everyday meaning, you normally do not write it as u jutro.

Yes, absolutely.

Serbian word order is fairly flexible, and changing the order often changes the focus rather than the basic meaning.

• Stižem ujutro. = neutral
• Ujutro stižem. = puts more emphasis on in the morning

So both are correct. The difference is mainly about what you want to highlight.

Without more context, it will usually be understood as one planned arrival.

But because stižem is an imperfective present form, it can also describe a habitual action if the context supports that.

For a clearly habitual meaning, Serbian would usually add something like:

• Stižem svakog jutra. = I arrive every morning.
• Obično stižem ujutro. = I usually arrive in the morning.

So by itself, Stižem ujutro most naturally sounds like one expected arrival.

A rough pronunciation guide is:

STEE-zhem OO-yoo-tro

A few useful sound notes:

• ž sounds like the s in measure
• j sounds like y in yes
• u is like oo in boot

So:

• stižem ≈ STEE-zhem
• ujutro ≈ oo-YOO-tro or OO-yoo-tro

The exact stress is not marked in normal writing, but this approximation is good enough for a learner starting out.