Learn Hardcore Croatian: Kad vidim svoje stare bilješke, vidim koliko sam već napredovala na tom tečaju. - When I see my old notes, I see how much I have already progressed in that course.

In most contexts they are interchangeable: Kad vidim… = Kada vidim…
Kada can sound a bit more formal or emphatic, and is preferred in careful writing or when you want to stress the time.
In everyday speech, kad is extremely common and completely correct here.

Why is it svoje stare bilješke and not moje stare bilješke?

Svoje is the reflexive possessive pronoun, used when the owner is the subject of the sentence (here: “I”).

General rule: if the subject owns the thing, use svoj (svoj, svoja, svoje…) rather than moj/tvoj/njegov…
- Kad vidim svoje stare bilješke… = When I see my own old notes.
Moje stare bilješke is not wrong, but svoje is more natural and is the default in such sentences.
With third person subjects, svoj is especially important to avoid ambiguity:
- On je pokazao svoje bilješke. = He showed his own notes.
- On je pokazao njegove bilješke. = He showed someone else’s notes (another man’s).

What case is svoje stare bilješke in, and why?

It’s in the accusative plural feminine.

The verb vidim (I see) takes a direct object in the accusative.
The noun bilješke is feminine plural; accusative plural form is also bilješke.
The pronoun and adjective have to agree with it:
- svoje – accusative plural feminine of svoj
- stare – accusative plural feminine of star
  So: (koga/što?) svoje stare bilješke as the object of vidim.

What exactly does bilješke mean? How is it different from bilješka or bilježnica?

In this sentence, svoje stare bilješke clearly means “my old notes”, not “my old notebooks”.

Why is there a comma after bilješke?

Because Kad vidim svoje stare bilješke is a dependent (subordinate) clause introduced by kad.

Rule: a subordinate clause introduced by kad/kada, ako, dok, jer, iako, etc. is normally separated by a comma from the main clause.
Here:
- Subordinate: Kad vidim svoje stare bilješke
- Main: vidim koliko sam već napredovala na tom tečaju.

So the comma is required in standard writing.

Why is vidim repeated? Could you leave the second vidim out?

The second vidim is the main verb of the main clause; strictly speaking, you need a main verb.

Full structure:
- Kad vidim svoje stare bilješke, (when-clause)
- vidim koliko sam već napredovala… (main clause)
In fast, informal speech people sometimes drop a repeated verb:
- Kad vidim svoje stare bilješke, (vidim) koliko sam već napredovala…
  Listeners can infer the missing vidim, but in written or careful language it’s better to keep it.

What does koliko do in the part vidim koliko sam već napredovala?

Koliko here is an interrogative/relative adverb meaning “how much / how far”.

It introduces a subordinate clause that functions as the object of vidim:
- vidim (što?) koliko sam već napredovala
Even though koliko usually appears in questions (Koliko si napredovala?), in this sentence it introduces an embedded clause, not a direct question.

Why is it sam napredovala and not just napredujem?

Sam napredovala is the perfect tense (past) of napredovati, formed with:

It expresses completed progress up to now, similar to English “I have progressed / I’ve already made progress”.

If you said:

vidim koliko napredujem – more like “I see how I am progressing (these days)” – focuses on the ongoing process, not on the accumulated result so far.
In this context, the perfect sam napredovala matches the idea “I see how much I have already advanced.”

Why does napredovala end in -la? Would a man say it differently?

Yes. In Croatian, the past participle agrees with the gender and number of the subject, even in the 1st person.

So the -la ending in napredovala tells you the speaker is female.

What does već add in koliko sam već napredovala? Can I omit it?

Već means “already”.

koliko sam već napredovala – “how much I’ve already progressed”, with a nuance that the progress is perhaps surprising or earlier than expected.
Without it:
- koliko sam napredovala – neutral “how much I’ve progressed”, without that “already / by now” feeling.

You can omit već grammatically; you just lose that nuance of “by this point / already”.

Is the word order koliko sam već napredovala fixed? Could I say koliko već sam napredovala or koliko sam napredovala već?

The natural, standard order is koliko sam već napredovala.

sam is a clitic (short, unstressed form of biti) and Croatian generally wants clitics in the second position in the clause, so it must come right after koliko:
- koliko sam… ✔
- koliko već sam… ✖ (sounds wrong/unnatural)
već is more flexible; you could move it, but other positions sound marked or awkward:
- koliko sam već napredovala – normal, neutral.
- koliko sam napredovala već – possible but sounds a bit unusual or emphatic in modern usage.

For learners, it’s best to stick with koliko sam već napredovala.

Why is it na tom tečaju and not u tom tečaju? And what case is tom tečaju?

Preposition choice
With tečaj (course), Croatian idiomatically uses na:
- na tečaju hrvatskog – “on a Croatian course”
  Saying u tečaju would sound strange or wrong; u is used for being inside something (a room, a building, a book), not for being “on a course”.
Case
Tom tečaju is locative singular masculine:
- Preposition na
  - locative → na (tom) tečaju
- taj tečaj → locative tom tečaju
  This phrase answers “where / in which context” you have progressed: on that course.