How important is knowing hangul before day 1?

Slow reading is enough. You do not need to be fluent — you need to not be decoding letters while the teacher is explaining grammar.

Why it matters: level 1 typically spends the first three to five days on hangul, then moves on and never looks back. Everything after that — the textbook, the whiteboard, the homework — is written in Korean. A student still sounding out syllables in week three is spending their attention on decoding instead of on the actual lesson, and the gap compounds fast.

Where you are now is fine. Sounding it out is the normal starting point and speed comes from exposure, not from more study. What closes the gap quickly:

1. Read signs. Subway station names, shop signs, bus destinations. Ten minutes a day of reading things that exist in the world beats an hour of drills.
2. Read out loud. Silent reading lets you skip; reading aloud forces every syllable.
3. Learn the batchim rules and the main sound changes. This is the actual difficulty, not the letters — why 좋아요 sounds like 조아요 and 한국말 like 한궁말. Two hours of study, then months of it clicking.
4. Menus. Genuinely useful and repetitive vocabulary.

Rough timeline: from where you are, two to four weeks of daily light practice gets you to comfortable reading speed. You have time.

One thing worth saying: do not use romanised Korean past your first week. It feels helpful and it permanently slows your reading. Students who lean on romanisation for their first months are still slow readers at level 3, and it is a hard habit to undo.

And do not let this stop you enrolling. Plenty of students arrive unable to read at all and catch up in the first fortnight. It just costs them two harder weeks.