Quando eu tiver tempo, vou passar na creche antes de falar com a babá.

Because Portuguese usually uses the future subjunctive after quando when the sentence refers to a future situation.

• Quando eu tiver tempo = When I have time
• Not Quando eu tenho tempo here, because that sounds more like a habitual/general meaning: When I have time, I usually...
• Not usually Quando eu terei tempo in this structure

The verb ter in the future subjunctive is:

• eu tiver
• você/ele/ela tiver
• nós tivermos
• vocês/eles/elas tiverem

This is very common after words like:

• quando = when
• se = if
• assim que = as soon as
• logo que = as soon as

So Quando eu tiver tempo is the natural way to say When I have time in a future sense.

Here, passar em or passar na/no often means to stop by or drop in at a place.

So:

• vou passar na creche = I’m going to stop by the daycare

It does not literally mean just pass through in this sentence.

A few examples:

• Vou passar no mercado. = I’m going to stop by the supermarket.
• Passei na casa dela. = I stopped by her house.

So in this sentence, the speaker plans to go to the daycare briefly before doing something else.

Na is a contraction of em + a.

• em a creche → na creche

Portuguese uses these contractions very often:

• em + o = no
• em + a = na
• de + o = do
• de + a = da
• a + a = à

So passar na creche literally contains em a creche, but that must contract to na creche.

Creche usually means daycare or nursery/day nursery for young children.

In Brazilian Portuguese, it refers to a place where very young children stay during the day while parents work or are busy.

It is different from:

• escola = school
• pré-escola = preschool
• berçário = nursery/infant room, depending on context

So creche is the natural word if the child is very young and goes to a daycare center.

Vou passar is the very common ir + infinitive future, similar to I’m going to stop by.

In Brazilian Portuguese, this is extremely common in everyday speech.

• vou passar = I’m going to stop by
• passarei = I will stop by

Both are possible, but vou passar sounds more natural and conversational in many everyday situations.

So:

• Quando eu tiver tempo, vou passar na creche... sounds very normal in spoken Brazilian Portuguese.

Because antes de + infinitive is normally used when the subject of both actions is the same.

In this sentence, the same person will:

1. stop by the daycare
2. speak with the babysitter/nanny

So Portuguese prefers:

• antes de falar com a babá

This is like saying:

• before speaking with the babysitter
• before talking to the babysitter

You can also have antes que + subjunctive, but that is used in different structures, especially when the subject changes or when the sentence is built differently.

Compare:

• Vou sair antes de dormir. = I’m going to leave before sleeping.
  same subject

• Vou sair antes que ele chegue. = I’m going to leave before he arrives.
  different subject

Yes, Portuguese has several possibilities, but falar com is very common when the idea is to speak with / talk to someone.

• falar com a babá = to talk to / speak with the babysitter

Other options exist:

• falar para a babá
• falar à babá (more formal or less common in everyday speech)

In everyday Brazilian Portuguese, falar com is one of the most natural choices when referring to having a conversation with someone.

It can mean either one, depending on context.

In Brazilian Portuguese, babá is the person who takes care of a child. In English, that might be:

• babysitter if it is temporary or occasional
• nanny if it is more regular or professional

Without more context, babá is just the childcare person. The exact English word depends on the situation.

Yes, it could be omitted.

Portuguese often leaves out subject pronouns when the verb already makes the subject clear:

• Quando eu tiver tempo...
• Quando tiver tempo...

Both are possible.

Why include eu?

• for clarity
• for emphasis
• just because speakers often say it

So the sentence could also be:

• Quando tiver tempo, vou passar na creche antes de falar com a babá.

That would still sound natural.

Not always. Usually in this sentence it means When I have time in a future, specific-plan sense.

• Quando eu tiver tempo, vou passar... = When I have time, I’m going to stop by...

It can sometimes be translated as whenever I have time in other contexts, but here it sounds more like a single future occasion, not a repeated habit.

If you wanted a repeated/habitual idea, the wording or context would usually make that clearer.

Because Quando eu tiver tempo is an introductory subordinate clause, and in Portuguese it is standard to separate it with a comma when it comes first.

So:

• Quando eu tiver tempo, vou passar na creche...

This is similar to English:

• When I have time, I’ll stop by the daycare...

If the order changes, punctuation may also change:

• Vou passar na creche quando eu tiver tempo.

That version usually does not need a comma.

Yes, but the meaning changes.

• ir à creche = to go to the daycare
• passar na creche = to stop by the daycare

So passar na creche suggests a brief visit or stop on the way, while ir à creche is more neutral and simply means going there.

Also notice the different prepositions:

• ir a + a creche → ir à creche
• passar em + a creche → passar na creche

It is the personal infinitive’s basic infinitive form, here just the regular infinitive: falar.

After antes de, Portuguese commonly uses the infinitive:

• antes de sair = before leaving
• antes de dormir = before sleeping
• antes de falar com a babá = before talking to the babysitter

Because the subject is understood and is the same as in the main clause, there is no need for a conjugated verb here.

Yes, it sounds natural and idiomatic.

Every part of it is very normal in Brazilian Portuguese:

• Quando eu tiver tempo = common future-subjunctive structure
• vou passar = very natural spoken future
• na creche = correct contraction
• antes de falar com a babá = natural infinitive structure

So this is a good, everyday Brazilian Portuguese sentence.