Learn Hardcore Indonesian: Saya melihat jam tangan dan berangkat lebih awal.

Past: tadi (earlier), barusan (just now), sudah/telah (already)
- Tadi saya melihat jam, lalu berangkat lebih awal.
- Saya sudah berangkat lebih awal.
Future: nanti, akan
- Nanti saya berangkat lebih awal.

Why isn’t saya repeated after dan?

Dropping the repeated subject is normal when it stays the same. Your sentence is understood as Saya melihat … dan (saya) berangkat …. Repeating it is also correct but less natural:

Saya melihat jam tangan dan saya berangkat lebih awal.

Does melihat mean “to see” or “to look at”?

Both, depending on context. With an explicit object like a watch, it means “look at/check.”

Saya melihat jam/jam tangan. = I looked at (checked) the time/my watch. For “to watch” (a movie, TV), use menonton, not melihat:
Saya menonton film.

Should I say jam or jam tangan here?

jam = clock/time in general; with melihat, it commonly means “check the time.”
jam tangan = wristwatch specifically. Both are fine; melihat jam is the most typical way to say “checked the time.”

How do I say “my watch” explicitly?

Neutral/formal: jam tangan saya
Informal: jam tanganku
Shorter: jam saya (often understood as “my watch” from context)

Is dan the best linker here, or should I use lalu/kemudian/terus?

dan = and (neutral link; sequence is inferred).
lalu/kemudian = then/after that (explicit sequence; kemudian is a bit more formal).
terus = then/and then (very informal). Example: Saya melihat jam, lalu berangkat lebih awal.

What’s the difference between berangkat and pergi?

berangkat = depart/set off (often scheduled or the start of a trip/activity).
pergi = go (general movement). Your sentence sounds more natural with berangkat. Examples:
Kereta berangkat pukul 7.
Saya pergi ke kantor. (I go to the office)
If you mean “go home,” use pulang.

What exactly does lebih awal mean? Is it comparative?

Yes. lebih = more, awal = early → lebih awal = earlier (than some expectation/normal time). If the comparison isn’t stated, it’s understood (e.g., than usual/than planned).

Explicit: lebih awal daripada rencana/dari biasanya.
“Earliest”: paling awal or terawal
“Too early”: terlalu awal

Can I use lebih cepat instead of lebih awal?

Generally no for “leaving earlier.” cepat = fast/quick (speed), not early (time). Use lebih awal for time. Note:

Jam saya lebih cepat 10 menit. = My watch is 10 minutes fast. (correct use of lebih cepat)
For departure time: berangkat lebih awal, not berangkat lebih cepat.

How do I say “I left 10 minutes earlier”?

Saya berangkat 10 menit lebih awal. Optional comparison:
Saya berangkat 10 menit lebih awal daripada rencana/dari biasanya.

Can I say lihat instead of melihat?

Yes, especially in casual speech:

Formal/neutral: Saya melihat jam.
Casual: Aku lihat jam. Very colloquial: Gue ngeliat jam. (Jakarta slang)

Do I need a preposition like “at,” e.g., melihat ke jam?

No. melihat takes a direct object; don’t add ke:

Correct: melihat jam/jam tangan
Not natural: melihat ke jam

Are there synonyms for jam tangan?

Yes: arloji (also spelled arloji in standard Indonesian). jam tangan is more common in everyday speech.

Is a comma before dan needed here?

No. Indonesian typically doesn’t use a comma before dan in this kind of coordination. If you want to highlight sequence, use lalu/kemudian (often with a comma): …, lalu berangkat …

Is there a smoother or more idiomatic way to say it?

Your sentence is fine. Very natural alternatives:

Saya melihat jam, lalu berangkat lebih awal.
Saya mengecek jam, lalu berangkat lebih awal. (more formal than cek)
Casual: Aku lihat jam, terus berangkat lebih awal.

Could I use aku instead of saya?

Yes. saya is neutral/formal; aku is informal/intimate; gue is Jakarta slang. Choose based on setting and relationship:

Formal/neutral: Saya melihat jam …
Informal: Aku lihat jam …
Very informal (Jakarta): Gue ngeliat jam …