I dag lærer vi at bruge “ikke ... før”, når noget først sker senere.

The dots show that this is a pattern, not a fixed two-word chunk that always stays together.

In Danish, ikke and før often have other words between them:

• Vi spiser ikke før klokken otte.
• Han kom ikke hjem før sent.
• Jeg forstod det ikke før bagefter.

So ikke ... før means: use ikke, then later in the sentence use før to show the time limit or point after which something happens.

Yes, very often.

That is usually the best English match:

• Vi går ikke før klokken ti. = We are not leaving until ten.
• Hun ringede ikke før i går. = She didn’t call until yesterday.

Literally, før often means before, but in the pattern ikke ... før, the whole idea is usually not until.

This is because Danish main clauses normally follow the verb-second rule.

That means the finite verb must come in the second position of the clause.

So:

• Vi lærer i dag ...
• I dag lærer vi ...

Both are possible, but when I dag is moved to the front for emphasis, the verb lærer must stay in second position, so the subject vi comes after it.

This is very common in Danish and often feels unusual to English speakers at first.

Because Danish often uses lære at + infinitive to mean learn to do something.

So:

• lære at bruge = learn to use
• lære at læse = learn to read
• lære at svømme = learn to swim

Compare:

• Jeg lærer dansk. = I am learning Danish.
• Jeg lærer at tale dansk. = I am learning to speak Danish.

So in your sentence, lærer vi at bruge means we are learning to use.

Here når means when in a general sense.

The sentence is explaining a rule: you use ikke ... før when something only happens later.

Why not the others?

• når = when, for general situations, repeated situations, or rules
• hvis = if
• da = when, but usually about a specific event in the past

So når is the natural choice because the sentence is talking about a general grammar situation, not one specific past event.

Not really in the usual English first sense.

In this kind of sentence, først often means something like:

• only
• not until then
• as late as

So noget først sker senere means that something happens only later, not earlier.

It adds emphasis to the idea of delay.

Compare:

• Han kommer først i morgen. = He is only coming tomorrow.
• Vi forstår det først senere. = We only understand it later.

So here først helps underline that the event does not happen yet; it happens later.

Noget literally means something, but in explanations like this it is often used very generally.

So når noget først sker senere means something like:

• when something
• when a thing
• when an event
• when something in general

It does not refer to one specific known thing. That is why noget is more natural than det here.

If the speaker meant a specific thing already known from context, det might be possible in another sentence, but here the explanation is general.

Yes, lærer is present tense.

Danish present tense often covers both:

• simple present: we learn
• present progressive: we are learning

So I dag lærer vi ... can be understood as either:

• Today we learn ...
• Today we are learning ...

In natural English, Today we are learning ... is usually the smoother translation in a teaching context, but the Danish form itself is just ordinary present tense.

Because når noget først sker senere is a subordinate clause.

In standard Danish writing, a subordinate clause is commonly separated with a comma:

• I dag lærer vi at bruge ikke ... før, når noget først sker senere.

So the comma marks the start of the clause introduced by når.

This is a normal feature of written Danish punctuation and something learners see very often.

Yes. It is a very common pattern.

A few examples:

• Jeg spiser ikke før senere.
  = I’m not eating until later.

• Hun kom ikke før klokken ni.
  = She didn’t arrive until nine.

• Vi ved det ikke før i morgen.
  = We won’t know until tomorrow.

• De åbner ikke før mandag.
  = They don’t open until Monday.

So the pattern is useful whenever you want to say that something happens only after a certain time point, not before it.