it's now or neverCHANCE/OPPORTUNITYused to say that if someone does not do something now, they will not get another chance to do it 机不可失，莫失良机 Quite suddenly, her mind was made up. It was now or never. 突然间她下定了决心。机不可失，时不再来。
it’s now or never• Twoflower, I thought, it's now or never.
→ it’s now or never at now1(SPOKEN SECT)