Quando tudo estiver arranjado, vamos finalmente convidar os amigos para jantar em casa.

Because after quando when you are talking about a future situation, Portuguese usually uses the future subjunctive.

So:

• Quando tudo está arranjado = when everything is arranged / whenever everything is arranged, more like a general or present-time idea
• Quando tudo estiver arranjado = when everything is arranged, referring to a specific point in the future

In this sentence, the invitation will happen later, after everything is ready, so estiver is the natural choice.

Estiver is the future subjunctive of the verb estar.

The full idea is:

• quando tudo estiver arranjado = when everything is ready / sorted / arranged

The future subjunctive is very common in Portuguese after words like:

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

especially when the action is still in the future.

Here, arranjado is the past participle of arranjar, but in this sentence it works very much like an adjective.

So estar arranjado means something like:

• to be arranged
• to be sorted out
• to be ready
• to be fixed up

In context, tudo estiver arranjado means everything is sorted out / ready.

This is a very common structure in Portuguese:

• estar + past participle

It often describes the resulting state of something.

It depends on context, and that is exactly why learners often notice this word.

In European Portuguese, arranjar and arranjado are very flexible. They can mean things like:

• to arrange
• to fix
• to sort out
• to get ready
• to tidy up

In this sentence, Quando tudo estiver arranjado most likely means:

• When everything is ready
• When everything has been sorted out
• possibly When the house is all set / tidied up

Since the next part is about inviting friends for dinner at home, it strongly suggests the house or preparations will be ready.

Vamos convidar is the very common ir + infinitive future, equivalent to we’re going to invite.

In Portuguese, especially in everyday speech, this is often preferred over the simple future:

• vamos convidar = we’re going to invite
• convidaremos = we will invite

Both are correct, but vamos convidar sounds more natural and conversational here.

So the sentence feels very natural in spoken European Portuguese.

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

Here:

• vamos convidar clearly means we are going to invite

So nós is unnecessary unless you want emphasis or contrast.

Compare:

• Vamos convidar os amigos. = We’re going to invite the friends.
• Nós vamos convidar os amigos. = We are going to invite the friends.
  This can sound more emphatic, depending on context.

Portuguese uses definite articles more often than English does.

So os amigos can mean:

• the friends
• or, in natural English, often just our friends / friends, depending on context

In this sentence, os amigos probably refers to a known group of friends, not just any friends at all.

This use of the article is very normal in Portuguese, even where English would often omit it.

Here para jantar means for dinner / to have dinner.

So:

• convidar os amigos para jantar = invite the friends for dinner
• more literally: invite the friends to dine

Portuguese often uses para + infinitive after verbs like convidar:

• convidar para almoçar = invite for lunch
• convidar para jantar = invite for dinner
• convidar para entrar = invite to come in

So yes, literally it is to dine, but in natural English the best translation is usually for dinner.

It can mean both, depending on context.

In this sentence, because they are inviting friends for dinner, em casa most naturally means:

• at our place
• at home
• at our house

So jantar em casa is have dinner at home.
And in this context, inviting friends para jantar em casa means inviting them to dinner at your home.

Because grammatically it agrees with tudo, not with an implied noun like a casa.

• tudo is treated as masculine singular
• so the participle/adjective is arranjado

That is why we get:

• Tudo está arranjado
• Quando tudo estiver arranjado

If the sentence used a casa, then it would be feminine:

• Quando a casa estiver arranjada

Because the sentence begins with a subordinate clause:

• Quando tudo estiver arranjado = when everything is ready

Then comes the main clause:

• vamos finalmente convidar os amigos para jantar em casa

In Portuguese, as in English, it is very common to put a comma after an initial clause like this.

So the comma helps separate:

1. the time clause
2. the main action

Finalmente means finally.

In this sentence it emphasizes that the invitation has probably been delayed until everything is ready.

So the feeling is:

• once everything is sorted out, then at last we’ll invite our friends over

Its position is natural here:

• vamos finalmente convidar...

That placement highlights the idea of finally before the main action.

Yes, absolutely.

• Quando tudo estiver pronto = When everything is ready
• Quando tudo estiver arranjado = When everything is arranged / sorted / ready

The difference is subtle:

• pronto is a more general ready
• arranjado suggests things have been put in order, sorted out, or prepared

In this context, both work, but arranjado gives a slightly stronger sense that preparations have been taken care of.