Learn Hardcore Indonesian: Ibu Dini berkata presentasi dimulai pukul delapan. - Mrs. Dini said the presentation starts at eight o'clock.

Ibu is an honorific/title for an adult or respected woman (roughly Ms./Mrs./Ma’am). When it’s part of a name, it’s capitalized: Ibu Dini.
ibu in lowercase by itself can mean mother. To say my mother, you’d say ibu saya.
The shortened, very common form is Bu: Bu Dini. It’s polite and slightly more casual than Ibu Dini.

Is berkata the same as bilang or mengatakan? Which should I use?

berkata = to say. Intransitive; commonly followed by a clause (optionally with bahwa) or by a recipient with kepada.
- Example: Ibu Dini berkata (bahwa) …
mengatakan = to state/say something. Transitive; usually followed by a direct object or a bahwa-clause.
- Example: Ibu Dini mengatakan bahwa …
bilang = to say. Very common and informal/neutral in speech.
- Example: Ibu Dini bilang …
To express tell someone, use memberi tahu/ngasih tahu (informal) or mengatakan kepada:
- Ibu Dini memberi tahu saya bahwa …
- Ibu Dini mengatakan kepada saya bahwa …

Do I need to add bahwa (that) after berkata?

It’s optional: berkata (bahwa) … Both are correct.
bahwa adds formality/clarity, especially in writing.
With mengatakan, bahwa is very common: mengatakan bahwa …
In casual speech, people often use kalau instead of bahwa: berkata kalau … (colloquial).

Why is it presentasi dimulai and not presentasi mulai? What’s the difference among mulai, memulai, and dimulai?

mulai (intransitive): begin/start (by itself).
- Presentasi mulai pukul delapan.
memulai (active transitive): start something.
- Panitia memulai presentasi pukul delapan. (The committee starts the presentation.)
dimulai (passive): be started (by someone/unspecified).
- Presentasi dimulai pukul delapan. All three are fine; choose based on whether you want an actor, a passive form, or a simple intransitive verb.

Can I mention who starts it? How?

Yes:

Is pukul delapan the same as jam delapan?

Both mean eight o’clock.
pukul sounds a bit more formal/careful (common in announcements).
jam is everyday speech and also means hour(s) for duration: tiga jam (three hours).
You can add pada in formal writing: pada pukul/jam delapan. Don’t use di before clock times here.

How do I specify AM or PM?

Indonesian doesn’t use AM/PM in the sentence; you add a time-of-day word:

pagi (morning), siang (late morning–afternoon), sore (late afternoon–early evening), malam (night).
Examples: pukul delapan pagi (8 a.m.), pukul delapan malam (8 p.m.).
In schedules you’ll also see 24‑hour times: 08.00 vs 20.00 (often written with a dot), sometimes with time zones like WIB/WITA/WIT.

Does pukul also mean to hit? Is that confusing here?

Yes, pukul as a verb means hit/strike. In the time expression pukul + number, it clearly means o’clock, so there’s no confusion.
As a time word, pukul functions like a noun; you’re safe using it in clock times.

Why is there no the before presentasi? How do I say the presentation?

Indonesian has no articles. presentasi can be a or the, depending on context.
To make it clearly definite, add a demonstrative or possessive:
- presentasi itu (that/the presentation)
- presentasinya (the presentation; literally its presentation)
- presentasi ini (this presentation)

Should there be a comma or quotation marks after berkata?

Your sentence is reported speech without quotes, which is fine.
For a direct quote, use a comma and quotation marks:
- Ibu Dini berkata, "Presentasi dimulai pukul delapan."
With bahwa, you normally don’t use quotes:
- Ibu Dini berkata bahwa presentasi dimulai pukul delapan.

Can I move the reporting phrase to the end, like Presentasi dimulai pukul delapan, kata Ibu Dini?

Yes:

Presentasi dimulai pukul delapan, kata Ibu Dini.
You can also use katanya (she said/it is said): Presentasi dimulai pukul delapan, katanya. Note that katanya can be vague about who said it unless context is clear.

Is dimulai one word? How do I tell when di is a prefix versus the preposition di?

dimulai is one word: di- (passive prefix) + mulai.
The preposition di (at/in/on) is separate from the next word: di rumah, di kantor.
Rule of thumb: if it’s location, di is separate; if it’s a verb in passive, di- attaches to the verb: ditulis, dibuat, dimulai.

How do I say She told me that the presentation starts at eight?

Several natural options:

Formal/neutral: Ibu Dini mengatakan kepada saya bahwa presentasi dimulai pukul delapan.
Common: Ibu Dini memberi tahu saya bahwa presentasi dimulai pukul delapan.
Informal: Ibu Dini bilang ke saya presentasi dimulai jam delapan.

How do I show will start, already started, or just started?

Add particles/adverbs:

Can I drop pukul/jam and just say delapan?

Best practice: include pukul or jam. Presentasi dimulai jam delapan/pukul delapan.
In casual speech, locals may say mulai delapan if the context is obvious, but for learners it’s safer to keep jam/pukul.

Do I need yang between presentasi and dimulai? What about word order like Berkata Ibu Dini…?

No yang is needed. Presentasi dimulai is a normal subject + passive verb. Adding yang makes it a relative clause and changes the meaning:
- Presentasi yang dimulai pukul delapan … = the presentation that starts at eight …
Word order:
- Natural: Ibu Dini berkata … or Kata Ibu Dini, …
- Berkata Ibu Dini … sounds literary/archaic and is not typical in everyday Indonesian.