早晚 has two distinct meanings: as a noun, it means 'morning and evening' (like 早晨 but covering both ends of the day). As an adverb, it means 'sooner or later' — more colloquial than 迟早 (chí zǎo) and less formal than 必将 (bì jiāng) or 势必 (shì bì). It implies inevitability with a sense of patience, not urgency.