Learn Hardcore Indonesian: Kami tiba lebih dahulu di peron.

lebih dahulu: earlier than someone else/before another event (precedence).
lebih awal: earlier than expected/scheduled time (earliness on a timeline).
lebih cepat: faster (speed), not inherently about being earlier in time (though context can sometimes blur it).

Kami = we (excluding the person you’re talking to).
Kita = we (including the person you’re talking to). Using kami here implies the listener was not part of the group that arrived at the platform.

Do I need to add “sudah” to show past time (We arrived)?

No. Indonesian doesn’t mark tense on verbs. Kami tiba... can mean “we arrived” or “we have arrived,” depending on context. Add sudah/telah to make completion explicit: Kami sudah tiba.... You can also add a time word like tadi (earlier) or kemarin (yesterday).

What’s the nuance difference between tiba, sampai, and datang?

tiba di = arrive at (slightly more formal/neutral; common in announcements or writing).
sampai di = arrive at (very common in speech; neutral/informal).
datang ke = come to (focus is on coming rather than the moment of arrival). Avoid “tiba ke” and “datang di.” In very casual speech, people may say nyampe for sampai.

Why is it “di peron” and not “ke peron”?

di marks location (at/in/on): you’re already there. Hence tiba di peron.
ke marks movement toward a place: pergi ke peron (go to the platform).