八時に

at eight o'clock

→ 8時
phrase Rare #40,857
at eight o'clock に marks the specific time when an action takes place.
JA: 八時に駅で会いましょう。
EN: Let's meet at the station at eight o'clock.

八時にお前んとこに行くから

I'll come over to your place at eight.

明日の朝八時に誘いに行きます

I'll come by to invite you at eight tomorrow morning.

会は八時に散会した

The meeting adjourned at eight.

明日八時に起こしてください

Please wake me up at eight tomorrow.