La bienvenida empezó temprano.

Because bienvenida is being used here as a noun, meaning something like the welcome or the welcoming event/moment, so it normally takes an article: la.

Compare:

• La bienvenida empezó temprano. = The welcome started early.
• Bienvenida, Ana. = Welcome, Ana. Here bienvenida is not a noun; it is being used more like an expression directed at someone.

So in this sentence, la is there because we are talking about the welcome as a thing or event.

In La bienvenida empezó temprano, bienvenida is a noun.

Even though bienvenido/bienvenida can also be an adjective, here it names an event or act of welcoming.

For example:

• una cálida bienvenida = a warm welcome
  Here bienvenida is clearly a noun.
• Ella es bienvenida aquí. = She is welcome here.
  Here bienvenida is an adjective.

So in your sentence, it is definitely a noun.

It is feminine because the noun bienvenida is grammatically feminine in Spanish, so it goes with la.

This does not mean the welcome itself is female in any real-world sense. It is just grammatical gender.

You can tell because:

• la bienvenida
• una bienvenida
• la cálida bienvenida

Many Spanish nouns ending in -a are feminine, and bienvenida follows that pattern.

Empezó is the preterite form of empezar for él/ella/usted.

That means the sentence is talking about a completed action in the past: it started.

Since la bienvenida is singular, the verb must also be singular:

• La bienvenida empezó... = The welcome started...

The subject is la bienvenida, which is treated like it in English, so Spanish uses the same verb form as for él/ella/usted.

Good question. Both are past tenses, but they give different views of the action.

• empezó = started
  This presents the beginning as a completed event.
• empezaba = was starting / used to start
  This is more descriptive, ongoing, or background-like.

So:

• La bienvenida empezó temprano.
  The welcome started early.
  This sounds like a clear event.
• La bienvenida empezaba temprano.
  The welcome was starting early / used to start early.
  This would need more context and sounds less natural on its own.

In this sentence, empezó is the normal choice because it marks the beginning as a specific completed moment.

The accent mark shows both pronunciation and meaning/form.

• empezó = he/she/it/you-formal started
• empiezo = I start
• empezo without an accent is not the correct standard spelling

The accent on -ó helps mark the correct stress and distinguishes this past-tense form.

So the accent is not optional here; it is part of the correct spelling.

Because temprano is being used as an adverb here, meaning early.

Adverbs do not change for gender or number, so it stays temprano.

Compare:

• La bienvenida empezó temprano.
  Here temprano describes when the action happened → adverb.
• una bienvenida temprana
  Here temprana describes the noun bienvenida → adjective, so it agrees in gender.

So in your sentence:

• empezó temprano = started early

Yes. Comenzó works very well here and means almost the same thing.

• La bienvenida empezó temprano.
• La bienvenida comenzó temprano.

Both are natural. In many contexts, empezar and comenzar are interchangeable.

A small difference in feel:

• empezar is often a bit more common and everyday
• comenzar can sound slightly more formal in some contexts

But both are correct.

Yes, but the original order is the most neutral and natural.

Standard order:

• La bienvenida empezó temprano.

You could also say:

• Temprano empezó la bienvenida.

But that sounds more literary, emphatic, or stylistically marked. It draws attention to temprano.

For most learners, the normal and safest order is:

• subject + verb + adverb
• La bienvenida empezó temprano.

La bienvenida is possible and correct, especially if you mean the welcome event, the reception, or the welcoming part of something.

But in many everyday situations, Spanish also often uses expressions with dar la bienvenida:

• Nos dieron la bienvenida temprano. = They welcomed us early.
• El acto de bienvenida empezó temprano. = The welcoming ceremony started early.

So La bienvenida empezó temprano is grammatical and natural in the right context, but depending on what exactly you mean, Spanish may also prefer a more specific phrase like el acto de bienvenida or a verb phrase with dar la bienvenida.

The subject is La bienvenida.

That is what started.

You can test it by asking:

• What started early?
  La bienvenida.

So the structure is:

• La bienvenida = subject
• empezó = verb
• temprano = adverb

This is why the verb is singular: the subject is singular.

Yes. Bienvenida can refer to different but related ideas:

• a welcome in a general sense
• a greeting of welcome
• a reception
• a welcoming event or ceremony

So in La bienvenida empezó temprano, the exact nuance depends on context. It could mean:

• the welcoming ceremony started early
• the reception started early
• the welcoming part of an event started early

The grammar stays the same, but the most natural English translation can vary a little depending on the situation.