Hurry up and finish your breakfast, or you'll be late for the bus.
You better finish you breakfast quickly, otherwise you'll miss your bus.
この場合、次のような言い方ができますよ。
ーHurry up and finish your breakfast, or you'll be late for the bus.
「早く朝ごはんを食べ終えないとバスに遅れるよ」
ーYou better finish you breakfast quickly, otherwise you'll miss your bus.
「早く朝ごはんを終えないと、バスに見逃すよ」
ご参考まで!