Since this word is made up of a single kanji, it uses the kun'yomi reading. You didn't learn that reading with the kanji, so here's a mnemonic to help you:
Just ahead of you are the tips of a saw and a key(さき). You have no idea what they're doing there, but both saws and keys have very sharp tips, so watch out you don't hurt yourself. Imagine yourself edging carefully past those saw and key tips.
You can differentiate this from 先ず (まず) because it doesn't have any hiragana on the end.
The tip of the pen got crushed.
Please go first.
There's a restaurant just ahead of us.
Nobody knows what the future holds.