Ég ætlaði að hrósa systur minni fyrr, en ég gerði það ekki fyrr en í dag.

Ætlaði is the past tense of að ætla, which often means to intend, to be going to, or to mean to.

So ég ætlaði að hrósa... means something like:

• I intended to praise...
• I was going to praise...
• I meant to praise...

In this sentence, it suggests a plan or intention in the past that was not carried out at the expected time.

Because ætla is commonly followed by að + infinitive.

So:

• ég ætlaði að hrósa = I intended to praise

This is a very common Icelandic pattern:

• Ég ætla að fara. = I’m going to go.
• Hún ætlaði að hringja. = She intended to call.

Here, hrósa is the infinitive verb.

Because the verb að hrósa takes the dative case for the person being praised.

The basic nominative form is:

• systir mín = my sister

But after hrósa, it must become dative:

• systur minni = my sister (dative)

So the sentence uses the correct case required by the verb.

Yes, að hrósa normally takes a dative object.

Examples:

• Ég hrósa honum. = I praise him.
• Hún hrósaði barninu. = She praised the child.
• Við hrósuðum kennaranum. = We praised the teacher.

So in your sentence:

• hrósa systur minni

is exactly what we expect grammatically.

Because possessive words like minn change for gender, number, and case.

Here, systur is:

• feminine
• singular
• dative

So minn must match that form, which is minni.

A few forms for comparison:

• systir mín = my sister (nominative)
• systur mína = my sister (accusative)
• systur minni = my sister (dative)

So minni is there because it agrees with systur in the dative.

Fyrr means earlier.

So:

• Ég ætlaði að hrósa systur minni fyrr
  = I intended to praise my sister earlier

It refers to an earlier point in time than the one at which the action actually happened.

The two instances do slightly different jobs:

• the first fyrr means earlier
• the expression ekki fyrr en means not until

So the sentence breaks down like this:

• Ég ætlaði að hrósa systur minni fyrr
  = I intended to praise my sister earlier
• en ég gerði það ekki fyrr en í dag
  = but I didn’t do it until today

This repetition is completely natural in Icelandic.

It means not until today.

This is a common Icelandic pattern:

• ekki fyrr en... = not until...

Examples:

• Ég kom ekki fyrr en klukkan tíu. = I didn’t arrive until ten o’clock.
• Hún skildi það ekki fyrr en seinna. = She didn’t understand it until later.

So here:

• ég gerði það ekki fyrr en í dag
  = I didn’t do it until today

Það means it/that, and here it refers back to the action of praising the sister.

So:

• ég gerði það literally = I did that
• more naturally = I did it

Instead of repeating að hrósa systur minni, Icelandic uses það as a stand-in.

English does the same thing:

• I meant to praise my sister earlier, but I didn’t do it until today.

Because Icelandic, like English, often avoids repeating the full verb phrase when it is already understood from the context.

So instead of saying something like:

• ...en ég hrósaði systur minni ekki fyrr en í dag

the speaker says:

• ...en ég gerði það ekki fyrr en í dag

This is smoother and more natural in many contexts. It works much like English do it or did it.

Icelandic main clauses usually follow the verb-second pattern, often called V2. That means the finite verb tends to come in the second position of the clause.

Here the clause starts with the subject:

• ég = subject
• gerði = finite verb

So the order is normal:

• ég gerði það ekki fyrr en í dag

Then ekki comes after the verb phrase element það here, giving:

• I did it not until today
  which in natural English becomes
• I didn’t do it until today

Sometimes in loose translation, yes, but intended to or meant to is usually more accurate.

Að vilja is the more direct verb for to want.

Compare:

• Ég ætlaði að hrósa henni. = I intended / meant to praise her.
• Ég vildi hrósa henni. = I wanted to praise her.

So ætlaði is more about intention or plan than simple desire.

Because the whole sentence is told from a point after the action has already happened.

• ætlaði = I had intended / I meant to
• gerði = I did

Even though í dag means today, the speaker is still talking about something that has already taken place earlier on that same day.

So the logic is:

• earlier, I intended to do it sooner
• but in fact I only did it today

Yes. En often means but when it connects two contrasting clauses.

Here the contrast is:

• I intended to praise my sister earlier
• but I did not do it until today

So en is functioning exactly as a coordinating conjunction showing contrast.

Yes. Að hrósa can mean to praise, to compliment, or to speak well of, depending on context.

So possible natural translations include:

• I intended to praise my sister earlier, but I didn’t do it until today.
• I meant to compliment my sister earlier, but I didn’t do it until today.

The exact English choice depends on the situation.

Here are the main dictionary forms:

• ég → I
• ætlaði → from að ætla
• að → infinitive marker, to
• hrósa → to praise / compliment
• systur → from systir = sister
• minni → from minn = my
• fyrr → earlier
• en → but / than depending on context
• gerði → from að gera = to do / make
• það → it / that
• ekki → not
• í dag → today

Looking up the dictionary forms can make the sentence much easier to understand.