Sorry to disagree with neenynanu but telling the time is on the u.k. national curriculum for both key stage 1 & 2. They start with analogue clocks - the hour and the half hour and by the end of year 6 children should be reading digital clocks, analogue clocks and converting between the two. They should be able to use time as a measure of an event, and understand the relationship between all units of time etc, etc.
But with your own child at home - What time do they eat? Go to bed? See daddy? See mummy? How long until they go in the bath? Use it, don't try and "teach" it.