Cuando llegue mi turno, voy a hablar con calma.

Because after cuando referring to a future action, Spanish normally uses the present subjunctive, not the present indicative or future tense.

So:

• Cuando llegue mi turno... = When my turn comes...
• not Cuando llega mi turno... if you mean a specific future moment
• not usually Cuando llegará mi turno... in this structure

A useful rule:

• cuando + indicative → habitual actions or things that are already real/factual
• cuando + subjunctive → future or not-yet-real actions

Compare:

• Cuando llega mi turno, me pongo nervioso.
  = When it’s my turn, I get nervous. (habitual)
• Cuando llegue mi turno, voy a hablar con calma.
  = When my turn comes, I’m going to speak calmly. (future)

Llegue is the present subjunctive form of llegar.

For llegar, the present subjunctive forms are:

• yo llegue
• tú llegues
• él/ella/usted llegue
• nosotros lleguemos
• vosotros lleguéis
• ellos/ellas/ustedes lleguen

Notice the spelling change in llegue and lleguen: the u is added so the g keeps its hard sound before e.

Spanish and English organize this idea differently.

In English, we often use a present form after when to talk about the future:

• When my turn comes, I’ll speak calmly.

Spanish treats that future event as something that has not happened yet, so it uses the subjunctive after cuando:

• Cuando llegue mi turno...

This is very common after time expressions when the action is still pending, such as:

• cuando
• en cuanto
• hasta que
• tan pronto como

Examples:

• Te llamo cuando llegue a casa.
• Lo haré en cuanto tenga tiempo.

Both are correct:

• voy a hablar
• hablaré

The first one uses the ir a + infinitive future, which is extremely common in everyday Spanish. It often sounds a bit more natural and conversational.

So these are both fine:

• Cuando llegue mi turno, voy a hablar con calma.
• Cuando llegue mi turno, hablaré con calma.

In many everyday contexts, voy a hablar feels a little more immediate or planned, while hablaré can sound a bit more neutral, formal, or simply more like the simple future. But in practice, both can work here.

Yes, absolutely.

That version is grammatically correct and natural. The difference is mainly style:

• voy a hablar → very common in conversation
• hablaré → also correct, sometimes a bit more formal or more straightforwardly future

A learner should understand and be able to use both.

Mi turno means my turn.

The noun turno is used for turns in a line, in a conversation, in a game, or in any sequence where people wait for their moment.

Examples:

• Es mi turno. = It’s my turn.
• Cuando sea tu turno, habla. = When it’s your turn, speak.
• Estoy esperando mi turno. = I’m waiting for my turn.

It can also mean a shift, especially at work:

• turno de noche = night shift

Because in Spanish, possessives usually go before the noun in normal, everyday sentences:

• mi turno
• tu libro
• su casa

Using el turno mío is not the normal choice here. Spanish can sometimes use possessive phrases after the noun for contrast or emphasis, but that is a different structure.

So the natural form is:

• Cuando llegue mi turno...

Con calma means something like:

• calmly
• without rushing
• in a calm way
• taking it easy

It is a very common expression in Spanish.

Examples:

• Hazlo con calma. = Do it calmly / Take your time.
• Vamos con calma. = Let’s go slowly / Let’s take it easy.
• Respondió con calma. = He/She answered calmly.

In your sentence, voy a hablar con calma means the speaker intends to speak in a calm, controlled way.

It could, but con calma is usually more natural and more common in everyday Spanish.

So:

• hablar con calma = very natural
• hablar calmamente = grammatically correct, but less common in ordinary speech

Spanish often prefers expressions like con + noun instead of an adverb ending in -mente.

Compare:

• escuchar con atención rather than atentamente in some contexts
• hablar con calma rather than calmamente

Because Spanish often omits subject pronouns when the verb already makes the subject clear.

In voy a hablar, the form voy already tells you the subject is yo.

So Spanish normally says:

• voy a hablar

rather than:

• yo voy a hablar

You can add yo for emphasis, contrast, or clarity:

• Cuando llegue mi turno, yo voy a hablar con calma, no a gritar.

But without emphasis, leaving it out is more natural.

The comma separates the introductory cuando clause from the main clause:

• Cuando llegue mi turno, / voy a hablar con calma.

This is standard punctuation in Spanish and also helps readability.

That said, punctuation can vary a little in short sentences, but using the comma here is normal and recommended.

Yes. That is also correct and natural.

Both versions work:

• Cuando llegue mi turno, voy a hablar con calma.
• Voy a hablar con calma cuando llegue mi turno.

The difference is mostly about focus:

• Starting with Cuando llegue mi turno highlights the time condition first.
• Starting with Voy a hablar con calma highlights the main action first.

Yes. Cuando sea mi turno is also correct and very common.

Compare:

• Cuando llegue mi turno... = When my turn comes...
• Cuando sea mi turno... = When it’s my turn...

Both are natural. The first uses llegar and imagines the turn as something that arrives. The second uses ser and identifies the moment as being your turn.

English speakers can think of them as very close in meaning.

Yes. It sounds natural in Spain.

A speaker in Spain might also say similar things like:

• Cuando llegue mi turno, hablaré con calma.
• Cuando sea mi turno, voy a hablar tranquilo.
• Cuando me toque, voy a hablar con calma.

That last one, Cuando me toque, is especially common in everyday speech and means When it’s my turn or literally When it touches me / when my turn comes up.