Learn Hardcore Spanish (Spain): En cuanto llegue a casa, enchufaré el móvil y te enviaré un mensaje. - As soon as I get home, I will plug in my phone and send you a message.

Because future time clauses introduced by conjunctions like en cuanto, cuando, hasta que, tan pronto como, después de que take the present subjunctive when the event is pending. The main clause can use the future, present, or ir a + infinitive, but the time clause uses present subjunctive.

Future/pending: En cuanto llegue a casa, te enviaré/te envío un mensaje.
Habitual: En cuanto llego a casa, te envío un mensaje.
Past: En cuanto llegué a casa, te envié un mensaje.

Could I use cuando instead of en cuanto? What’s the difference?

Yes. En cuanto (and tan pronto como) means “as soon as,” stressing immediacy. Cuando is more neutral: “when.” All still take the subjunctive for future events:

Cuando/En cuanto/Tan pronto como llegue a casa, te escribiré. Using cuando softens the sense of “right away.”

Why is it a casa and not en casa, a la casa, or a mi casa?

With llegar, use the preposition a for destination: llegar a.
A casa = “home,” and by default means the speaker’s home.
En casa = “at home” (state of being there), not movement: Estoy en casa.
A la casa is “to the house” (a specific house, not necessarily yours).
A mi casa emphasizes whose home it is: a mi casa, not someone else’s.

Why use the future (enchufaré, enviaré)? Can I say the present or ir a + infinitive instead?

All three are correct:

Simple future (promises/plans): Enchufaré el móvil y te enviaré un mensaje.
Present (very common in Spain for near future): Enchufo el móvil y te envío un mensaje.
Ir a + infinitive (near future/colloquial): Voy a enchufar el móvil y te voy a enviar un mensaje / voy a enviarte un mensaje. Choose based on tone and immediacy; present is very natural in everyday Peninsular Spanish.

Is enchufar el móvil what people in Spain actually say?

It’s understood and fine. Very common alternatives in Spain are:

Poner a cargar el móvil / Poner el móvil a cargar
Cargar el móvil You’ll also hear the colloquial verb enchufar in many contexts, but the “charge” expressions above are extremely common.

Why el móvil and not mi móvil? Are both correct?

Both are correct. Spanish often uses the definite article with personal belongings when ownership is obvious from context. Enchufaré el móvil naturally implies “my phone.” Use mi móvil if you need to emphasize whose phone it is or to contrast with someone else’s.

What’s the difference between móvil, celular, and teléfono?

Móvil: the normal word for “cell phone” in Spain.
Celular: the normal word in most of Latin America.
Teléfono: generic “phone” (mobile or landline); teléfono móvil is more formal/explicit.

In te enviaré un mensaje, what does te do? Could it be le?

Te is the indirect object pronoun “to you” (informal, singular). Other options:

Formal singular (usted): Le enviaré un mensaje.
Informal plural (vosotros, Spain): Os enviaré un mensaje.
Formal plural (ustedes): Les enviaré un mensaje. If you also replace the direct object (the thing sent) with a pronoun, remember the “le/les + lo” rule becomes se lo: Se lo enviaré (a usted/a ustedes).

Can I say te lo enviaré instead of te enviaré un mensaje?

Only if lo refers to a specific, previously mentioned message (or thing). You either keep the noun or replace it:

Keep noun: Te enviaré un mensaje.
Replace noun: ¿El mensaje? Te lo enviaré. Don’t mix an indefinite noun with a redundant object pronoun: “Te lo enviaré un mensaje” is incorrect.

Where do object pronouns go with these verbs? Is Lo voy a enchufar = Voy a enchufarlo?

Yes.

With a single, conjugated verb: pronoun before it: Lo enchufaré.
With ir a + infinitive: either before the conjugated verb or attached to the infinitive: Lo voy a enchufar / Voy a enchufarlo.
With gerunds and affirmative commands, you can attach: Estoy enchufándolo; Enchúfalo.

Is the comma after the introductory clause required?

Standard Spanish punctuation uses a comma when the dependent clause comes first: En cuanto llegue a casa, ... If the main clause comes first, you normally don’t use a comma: Te enviaré un mensaje en cuanto llegue a casa.

Why not llegué (with an accent)? How do llegue and llegué differ?

Llegue (no accent) = present subjunctive (yo/él/ella/usted). Used after time conjunctions referring to future: En cuanto llegue...
Llegué (accent) = preterite indicative, 1st person singular “I arrived”: En cuanto llegué a casa, enchufé el móvil.

How do I pronounce llegue and enchufaré?

Llegue: in most of Spain, ll sounds like English “y.” The gue keeps a hard g; the “u” is silent. Sounds like “yeh-GEH.”
Enchufaré: stress the last syllable because of the accent: en-chu-fa-REH.

Could I say Nada más llegar a casa, ... or Al llegar a casa, ... instead of En cuanto llegue a casa, ...?

Yes.

Nada más + infinitive = “as soon as”: Nada más llegar a casa, te enviaré un mensaje.
Al + infinitive = “upon (doing)”: Al llegar a casa, te enviaré un mensaje. The first stresses immediacy; the second is neutral about how quickly the next action happens.

Does y imply I will plug in first and then send, or is it just “and”?

It’s just “and,” but listeners usually infer a natural sequence. If order matters, make it explicit:

En cuanto llegue a casa, primero te enviaré un mensaje y luego enchufaré el móvil.
En cuanto llegue a casa, enchufaré el móvil y después te enviaré un mensaje.

Is there any difference between enviar and mandar here?

Not in meaning. Both are common. In Spain, mandar is very frequent in casual speech, especially for apps: Te mando un WhatsApp. Enviar can feel a bit more formal or neutral.