Quando avrò finito lo spuntino, passerò dall’edicola a comprare il giornale.

Because avrò finito is the future perfect (futuro anteriore), and it shows that one future action will be completed before another future action.

In this sentence:

• avrò finito lo spuntino = I will have finished the snack
• passerò dall’edicola = I will stop by the newsstand

So the idea is:

1. first I finish the snack
2. then I go to the newsstand

If you said Quando finirò lo spuntino, it would sound less natural here because the sentence is specifically focusing on the snack being already completed before the next action happens.

Avrò finito is made with:

• the future tense of avere → avrò
• the past participle of finire → finito

So:

• avere → avrò
• finire → finito
• together: avrò finito

This is the normal pattern for the futuro anteriore:

• avrò mangiato = I will have eaten
• sarai arrivato/a = you will have arrived
• avremo visto = we will have seen

That is a very common question for English speakers.

In English, after when, we usually use the present to talk about the future:

• When I finish, I’ll go...
• not usually When I will finish...

Italian works differently. Italian often uses the future in both parts when the meaning is future:

• Quando avrò finito..., passerò...

So this is normal Italian grammar, even though English uses a different tense pattern.

Here Quando means when in the sense of at the moment that.

So:

• Quando avrò finito lo spuntino = When I have finished / once I’ve finished the snack

It introduces a time clause telling you when the second action will happen.

Spuntino means snack or light snack.

It takes lo because spuntino begins with sp- followed by a consonant. In Italian, nouns that begin with:

• s + consonant
• z
• ps
• gn
• and a few others

often take lo in the singular masculine form.

So:

• lo spuntino
• lo studente
• lo sport
• lo zaino

Not il spuntino, but lo spuntino.

Passerò dall’edicola means something like:

• I’ll stop by the newsstand
• I’ll go by the newsstand
• I’ll drop by the kiosk/newsstand

The verb passare da often means to stop by, to pass by, or to go via a place.

So this is not just literally walking past it. In context, it usually suggests a brief stop there.

Because the verb expression here is passare da un posto.

So:

• passare da casa
• passare dal panettiere
• passare dall’edicola

The da is part of the way Italian expresses stopping by or going via a place.

Dall’edicola is made from:

• da + la edicola → dalla edicola
• then because edicola starts with a vowel, it becomes dall’edicola

So the apostrophe is just the normal elision.

Edicola usually means a newsstand, newspaper kiosk, or small stand/shop that sells newspapers, magazines, and often other small items.

So comprare il giornale all’edicola is a very natural everyday Italian idea.

Here a comprare expresses purpose:

• passerò dall’edicola a comprare il giornale
• I’ll stop by the newsstand to buy the newspaper

In Italian, after verbs of movement or similar actions, a + infinitive can mean in order to / to do something.

Examples:

• vado al supermercato a fare la spesa
• sono uscito a prendere un caffè
• passo da te a salutarti

So a comprare tells us why the speaker is going/stopping there.

Yes, per comprare il giornale is possible, but a comprare is very natural after a motion idea like passare.

Very roughly:

• a comprare often feels tightly linked to the movement/action
• per comprare can also express purpose, but may sound a bit more general or explicit

In this sentence, a comprare is probably the most idiomatic choice.

Italian often uses the definite article where English may omit it.

So:

• comprare il giornale = buy the newspaper / buy a paper

Even if English sometimes says buy a newspaper or just buy the paper, Italian commonly uses il here.

This does not necessarily mean one specific newspaper has already been mentioned. It can simply sound like the normal way to refer to the item in context.

Yes. It is required because la edicola becomes l’edicola, and therefore:

• da + l’edicola = dall’edicola

Italian normally uses elision before a vowel in forms like this.

Compare:

• dalla scuola
• dall’edicola
• dall’amico
• dall’ufficio

Because the sentence begins with a subordinate time clause:

• Quando avrò finito lo spuntino, ...

After that introductory clause, Italian commonly places a comma before the main clause:

• ..., passerò dall’edicola a comprare il giornale.

This is very similar to English punctuation:

• When I’ve finished my snack, I’ll stop by the newsstand...

If the order were reversed, the comma might be less necessary:

• Passerò dall’edicola a comprare il giornale quando avrò finito lo spuntino.

Not if you mean a future situation.

Quando ho finito is present perfect in form, but in Italian it normally refers to a past completed action, not the future. So it would not fit well here.

To talk about the future, Italian prefers:

• Quando finirò...
• Quando avrò finito...

And in this sentence, quando avrò finito is best because it clearly shows the finishing happens before the next future action.

Both can express sequence, but they are structured differently.

• Quando avrò finito lo spuntino, passerò... = When I’ve finished the snack, I’ll stop by...

• Dopo aver finito lo spuntino, passerò... = After finishing / after having finished the snack, I’ll stop by...

The first uses a full clause with a subject and verb. The second uses dopo + infinitive phrase.

Both are correct, but Quando avrò finito... sounds very natural and direct in everyday speech.