There are two attributes of events that can be measured: time of occurrence and length of duration. You can begin by describing the time of occurrence by giving a time span. It happened today, in the morning, in October. Young children need to develop the vocabulary of days, months and seasons of the year.
Children can tell which of the events take longer (duration) if their lengths are greatly different. Does it take longer to brush your teeth or read a story? If the events are similar in duration, children can tell which lasts longer if they both begin at the same time (note the similarity to deciding which object is longer when both are placed on a baseline). You can think od many contests that use this idea: whose paper plane flew longer; whose eyes were shut longer; who hopped for a longer time.