Learn Hardcore Indonesian: Sesi pagi dimulai pukul delapan. - The morning session starts at eight o'clock.

dimulai is passive: it focuses on the event (the session) rather than who starts it. Very common in schedules and announcements.
Sesi pagi mulai pukul delapan is also correct and a bit more neutral/straight.
If you want to name the doer, use active: Panitia memulai sesi pagi pukul delapan (The committee starts the morning session at eight).

Should di be written together in dimulai, or split as di mulai?

Write it together: dimulai. Here di- is a verb prefix forming the passive.
Write di separately only when it’s the preposition meaning in/at/on, e.g., di rumah, di Jakarta.
So: dimulai (correct), not di mulai (wrong).

What’s the difference between pukul and jam?

Both can introduce clock times: pukul delapan = jam delapan = 8 o’clock.
pukul feels a bit more formal/written; jam is very common in speech.
Only jam is used for durations: dua jam = two hours (you can’t say dua pukul).
Note: pukul also means “to hit” as a verb; context disambiguates.

Can I add pada before the time?

Yes: Sesi pagi dimulai pada pukul delapan (more formal).
You can also say pada jam delapan.
Avoid di jam/delapan for clock times; use pada or nothing: (pada) pukul/jam delapan.

Does this mean 8 a.m. or 8 p.m.?

Because it’s sesi pagi (morning session), it implies 8 a.m.
To be explicit, you can say pukul delapan pagi (8 a.m.) or pukul delapan malam (8 p.m.).

Can I move the time phrase to another position?

Yes. All are natural:
- Sesi pagi dimulai pukul delapan.
- Pukul delapan, sesi pagi dimulai.
- Sesi pagi mulai pukul delapan.
- Sesi pagi dimulai pada pukul delapan.

How do I say “sharp,” “about,” or “no later than” with a time?

Sharp/exact: pukul delapan tepat or tepat pukul delapan.
About/around: sekitar/kira-kira pukul delapan.
No later than: selambat-lambatnya pukul delapan or paling lambat pukul delapan.

How do I say 8:05, 8:30, 8:45 in Indonesian?

8:05 = pukul delapan lewat lima (or 08.05/08:05).
8:30 = pukul setengah sembilan (literally “half to nine,” i.e., 8:30). Also possible: delapan tiga puluh (neutral/digital).
8:45 = pukul sembilan kurang lima belas or pukul sembilan kurang seperempat. Also possible: delapan empat puluh lima.

Why is 8:30 said as setengah sembilan and not setengah delapan?

Indonesian (like German) counts “half to the next hour.” Setengah sembilan = half of nine = 8:30.
This is very natural in speech. Digital style (delapan tiga puluh) is also understood.

Can mulai work as “starting from/since”?

Yes. As a preposition-like marker: Mulai pukul delapan, gerbang ditutup (Starting at eight, the gate is closed).
For “since” emphasizing duration from a point in the past, sejak is common: Sejak pukul delapan, hujan turun.

Is bermula used in Indonesian?

bermula is more Malay. In Indonesian, prefer mulai/dimulai/memulai.

Do I need an article for “the” morning session?

Indonesian has no articles. Sesi pagi can mean “the morning session” or “a morning session,” depending on context.

If I want to name who starts the session, how do I say it?

Active voice: Panitia memulai sesi pagi pukul delapan.
Passive with agent: Sesi pagi dimulai oleh panitia pukul delapan. (grammatical but heavier; active sounds more natural here)

Is it okay to drop pukul/jam and just say the number?

For clock time, include pukul or jam. Sesi pagi dimulai delapan sounds incomplete.
Natural: Sesi pagi dimulai jam delapan or … pukul delapan.

Is sesi the best word here? Are there alternatives?

sesi is standard for conferences, training, exams, etc.
Depending on context, you might see kelas pagi (morning class), sift/shift pagi (work shift), gelombang pagi (batch/wave), or acara pagi (morning program).

How do I write the time with numerals?

All of these are common: pukul 8, pukul 08.00, pukul 08:00. Formal Indonesian often uses a dot: 08.00.
In casual writing/speech: jam 8 is very common.

Any quick pronunciation tips?

Vowels are pure; stress typically falls near the last syllable (but not strongly).