Otkad imam novo šiljilo, olovka mi je uvijek spremna za pisanje.

Otkad means since or ever since.

In this sentence, it introduces the starting point of a situation that still continues now:

• Otkad imam novo šiljilo... = Since I have had / ever since I got a new sharpener...

A close synonym is otkako. In everyday Croatian, both are common.

Croatian often uses the present tense for a state that began in the past and still continues now.

So:

• Otkad imam novo šiljilo...
  literally: Since I have a new sharpener...

In natural English, we often switch to:

• Since I got a new sharpener...
• Since I’ve had a new sharpener...

Croatian does not need a separate present perfect here. The plain present works because the situation is still true.

Šiljilo means sharpener, especially a pencil sharpener.

It comes from the verb šiljiti, meaning to sharpen.

So:

• novo šiljilo = a new sharpener

Because šiljilo is a neuter noun, and the adjective has to agree with it in gender, number, and case.

So:

• masculine: novi
• feminine: nova
• neuter: novo

Since šiljilo is neuter singular, the correct form is:

• novo šiljilo

Olovka usually means pencil in modern standard Croatian.

If you want to say pen, the usual word is kemijska olovka or just kemijska in everyday speech.

So in this sentence:

• olovka mi je uvijek spremna za pisanje
  = my pencil is always ready for writing

Here mi is the dative clitic meaning to me, but in sentences like this it often expresses possession:

• olovka mi je... = my pencil is...

Literally, it is something like:

• the pencil is to me...

This is a very common Croatian way to say my / your / his / her in a more natural, conversational style.

Compare:

• Moja olovka je uvijek spremna za pisanje. = My pencil is always ready for writing.
• Olovka mi je uvijek spremna za pisanje. = also My pencil is always ready for writing.

The second version sounds very natural.

Because mi and je are clitics. Croatian clitics usually go in the second position of the clause.

So in:

• olovka mi je uvijek spremna...

the word olovka comes first, and then the clitics mi je come right after it.

This is normal Croatian word order.

You will often see similar patterns like:

• Brat mi je kod kuće. = My brother is at home.
• Auto mi je star. = My car is old.

Because spremna is an adjective agreeing with olovka, which is feminine singular.

The adjective spreman / spremna / spremno means ready.

Agreement:

• masculine: spreman
• feminine: spremna
• neuter: spremno

Since olovka is feminine:

• olovka je spremna

Uvijek means always.

So:

• olovka mi je uvijek spremna
  = my pencil is always ready

Its position is flexible, but the version in the sentence is very natural. Because Croatian word order is more flexible than English, you may see adverbs like uvijek move around for emphasis.

Za pisanje means for writing.

• za = for
• pisanje = writing

Pisanje is a verbal noun, built from the verb pisati (to write).

So:

• spremna za pisanje = ready for writing

Very literally, it means ready for the act of writing.

In Croatian, after za you normally use a noun phrase, not an infinitive.

That is why Croatian uses the verbal noun:

• za pisanje = for writing

not:

• za pisati ✘

This is similar to English using an -ing form after for:

• for writing
• not usually for to write

Yes. That is grammatically correct.

Compare:

• Moja olovka je uvijek spremna za pisanje.
• Olovka mi je uvijek spremna za pisanje.

Both mean basically the same thing: My pencil is always ready for writing.

The version with mi is often more natural and idiomatic in everyday Croatian, while moja olovka can sound a bit more explicit or emphatic.

Yes. The idea is:

• I now have a new sharpener.
• Because of that, my pencil is always sharpened and usable.

So the first part gives the reason or starting point:

• Otkad imam novo šiljilo... = Since I got/have had a new sharpener...

And the second part gives the ongoing result:

• olovka mi je uvijek spremna za pisanje. = my pencil is always ready for writing.

So the whole sentence expresses an ongoing benefit that started when the speaker got the sharpener.