Koreans use it when they arrive before the expected time and want to let others know politely.
Yes. "일찍 왔어요 (iljjik wasseoyo)" is polite and natural. You can also say "일찍 왔어 (iljjik wasseo)" casually.
You can say "I'm early" — 일찍 왔습니다 (iljjik wasseumnida).
일찍 왔어요 means "I'm early". It's a polite way to say you arrived before the expected time.
1. Before appointments: Arriving early at cafe or office.
2. At work / school: Letting others know you're ready.
3. For travel: At airport or station early.
I'm early. Please come slowly.
I'm early. Meeting preparation done. (Formal)
I came earlier than appointment. I'll wait at cafe. (Casual)
It's good you came early.