Først når vi har læst bogen, drøfter vi temaet.

Først når means only when or not until.

So the idea is:

• first, we read the book
• only after that, we discuss the theme

A very close English version is:

Only when we have read the book do we discuss the theme.

It adds a stronger sense of sequence than just når by itself.

This is because Danish is a verb-second language in main clauses.

The first element in the sentence is the whole subordinate clause:

Først når vi har læst bogen

After that, the finite verb of the main clause must come next, so you get:

drøfter vi temaet

Pattern:

• first position: Først når vi har læst bogen
• second position: drøfter
• then subject: vi

This is very common in Danish. Compare:

• Vi drøfter temaet.
• I morgen drøfter vi temaet.
• Når vi er klar, drøfter vi temaet.

Har læst is the present perfect of læse.

It is used here because the reading must be completed before the discussion happens. The sentence is not just about reading in general; it is about the book being finished first.

So:

• vi har læst bogen = we have read the book
• then: we discuss the theme

Even though the whole situation may refer to the future, Danish often uses the perfect in a clause like this to show completed action before another action.

Danish often does not use a special future tense the way English sometimes does. Very often, the present tense or present perfect is enough, especially when the time relationship is already clear.

Here the sentence already shows the order of events:

1. we have read the book
2. we discuss the theme

So Danish does not need something like will have read in order to make sense.

This is quite natural Danish.

Når usually means when, while hvis means if.

In this sentence, the speaker treats reading the book as something expected or planned, not just a possibility. That is why når is used.

• Når vi har læst bogen, ... = When we have read the book, ...
• Hvis vi læser bogen, ... = If we read the book, ...

So når sounds right because the reading is presented as the point at which the discussion will happen.

In Danish, the definite article is often added as an ending to the noun.

So:

• bog = book
• bogen = the book

and

• tema = theme/topic
• temaet = the theme/topic

This is one of the basic features of Danish nouns. Instead of putting the before the noun, Danish often attaches the definiteness to the end.

Yes, drøfte is a fairly formal or academic word meaning discuss.

So drøfter vi temaet sounds like:

• classroom language
• academic discussion
• formal conversation

In more everyday speech, people might also say things like:

• snakker om temaet
• taler om temaet
• diskuterer temaet

But drøfte is perfectly natural, especially in school or literary contexts.

Yes. A common alternative is:

Vi drøfter ikke temaet, før vi har læst bogen.

That means:

We do not discuss the theme until we have read the book.

This expresses almost the same idea, but with a different structure.

The original sentence with Først når ... puts stronger emphasis on the condition and timing.

The comma separates the subordinate clause from the main clause:

• Først når vi har læst bogen = subordinate clause
• drøfter vi temaet = main clause

So the comma helps show where the first clause ends and the main statement begins.

It is also useful because the word order changes after the subordinate clause, and the comma makes that easier to see.

It would be similar, but not exactly as strong.

• Når vi har læst bogen, drøfter vi temaet = When we have read the book, we discuss the theme
• Først når vi har læst bogen, drøfter vi temaet = Only when we have read the book do we discuss the theme

Adding først makes the restriction stronger. It clearly implies not before that point.