Dutch clock time uses a quarter-to, quarter-past and half system anchored to the next hour rather than the previous one for half. This is the most famous Dutch time peculiarity: half drie means half past two in English — halfway to three — not half past three. Quarter past two is kwart over twee. Quarter to three is kwart voor drie. Twenty past two is tien voor half drie, meaning ten minutes before half three (i.e. 2:20). This system becomes natural with practice.
The 24-hour clock is used in formal contexts, transport schedules and official announcements: veertien uur dertig. In everyday speech the 12-hour reference suffices: om drie uur with context making the time of day clear. Approximate times: tegen tienen (around ten), rond middernacht (around midnight), ergens in de ochtend (sometime in the morning). These approximate forms are very common in natural Dutch conversation.
Useful time vocabulary: nu (now), straks (in a while or later), dadelijk (shortly), zo (in a moment), zonet (just now), net (just), al (already), nog (still or yet), ooit (ever), nooit (never), soms (sometimes), vaak (often), altijd (always), zelden (seldom). The distinction between straks and dadelijk is subtle: straks is vaguer and can mean later today or in a while, while dadelijk implies very soon. Context and tone clarify the difference in practice.