Javit ću ti točno vrijeme sastanka čim ga saznam.

This is how the Croatian future tense is formed with many verbs.

The verb is javiti and the future auxiliary is ću. When ću comes right after an infinitive ending in -ti, the final -i drops:

• javiti + ću → javit ću

So javit ću means I will inform / I will let know.

If the auxiliary comes before the infinitive, then the full infinitive stays:

• Ja ću ti javiti...

Both are correct.

Ti is the short dative form of you. Here it means to you.

The verb javiti often works like this:

• javiti nekome nešto = to tell someone something / to let someone know something

So:

• Javit ću ti... = I’ll let you know...

Croatian does not have articles like a and the.

So Croatian simply says:

• točno vrijeme sastanka

and context tells you whether it means:

• the exact time of the meeting
• an exact time of the meeting

In this sentence, the meaning is naturally definite, so in English we translate it with the.

Here it is an adjective, not an adverb.

It agrees with vrijeme, which is a neuter singular noun:

• točan = masculine
• točna = feminine
• točno = neuter

So:

• točno vrijeme = exact time

It only looks like an adverb because many Croatian adverbs and neuter adjective forms have the same ending.

Because sastanka is the genitive singular form of sastanak.

Croatian often uses the genitive after another noun to show a relationship like of the meeting:

• vrijeme sastanka = the time of the meeting
• literally: time of meeting

So sastanka is there because vrijeme is being specified: it is the meeting’s time.

Čim means as soon as.

It suggests immediacy:

• čim ga saznam = as soon as I find it out / as soon as I learn it

You could use kad in some similar sentences, but kad is more general and means when.
Čim is more specific: it emphasizes that one action happens immediately after the other.

Because after time words like čim and kad, Croatian normally uses the present tense for future meaning.

So:

• čim ga saznam literally looks like as soon as I find it out
• but it means as soon as I find out

English actually does something similar:

• I’ll tell you as soon as I know
• not as soon as I will know

So this structure is very normal in Croatian.

Ga is the short accusative pronoun meaning it.

Here it refers to točno vrijeme sastanka — the exact meeting time.

Instead of repeating the whole phrase, Croatian uses a short pronoun:

• čim ga saznam = as soon as I find it out

That sounds much more natural than repeating the full noun phrase again.

Because the short pronoun ga is also used with neuter it in this kind of structure.

So even though vrijeme is a neuter noun, the short object pronoun is still:

• ga

That is normal Croatian usage.

These are clitics: short unstressed words that usually cannot stand alone and tend to appear near the beginning of a clause.

In this sentence:

• ću = future auxiliary
• ti = to you
• ga = it

Croatian has fairly strict patterns for where clitics go, so learners often just have to get used to them.

That is why you get:

• Javit ću ti...
• čim ga saznam

and not random word orders.

Because they fit the meaning and the aspect very well.

• javiti = to inform / let someone know
• saznati = to find out / learn

Both describe single, completed actions, which is exactly what this sentence needs:

• first I find out
• then I let you know

A verb like znati would mean to know, which is a state, not the moment of finding something out. So saznati is the natural choice here.