Have you ever considered how you view time? When someone says you have a meeting at 9 AM, do you view it as an obligation to be there at that time? Five minutes before? Within ten minutes? Would you say time is money? Would you say that you spent, saved, invested, or wasted time? Is the present the most important? What are your opinions of the past or the future?
We all view time a little bit differently--not only how it passes, but how it affects us. We place different values on how long we should spend on activities, consider time more or less urgent, have different opinions on timeliness and meetings...the list goes on. Some of us wear watches and have wall-clocks, while others can leave their watch set at completely the wrong time and not notice.
Different societies have different perceptions of time. For some, time is linear. For others, time moves in never-ending cycles. Some societies depend on clocks, while others move with the natural rhythms of the day and the year.
The possibilities for the use of time in your book are nearly endless. How can you bring your characters into conflict using their differing perceptions of time? Does one character value time differently and is late to every meeting? Does someone think decisions should be approached more slowly while the other character views every moment as precious?
How do your characters keep track of time? Do they have calendars? Are they solar or lunar based? Do they rely on cycles of the moon to determine months? When does the day start--7AM each day, or at the break of dawn? Do they meet at 0200, the second watch of the night, or when a certain star meets the horizon? Do they measure seconds? Minutes? Or degrees of the sun?
When does the year begin or end? Does it correspond with something?
Do your characters think they can speed things up? (The American who wants to rush through traffic.) Or is time inevitable and will move at its own pace? (The farmer who cannot change how his crops grow).
Does your world have time zones? Daylight savings time? If you're dealing with different planets, do they have different lengths of days and years? How do your characters reconcile that? Do your characters have weeks--that odd unit of measurement?
Do characters keep the same schedule each day--are you expected to sleep for a certain period every day, or is there a different schedule? Does everyone start the day at the same time across the globe? Or is it dependent on sunrise? Do factories have a second or third shift that is less desirable? Are certain activities expected at certain times--bathing morning or evening, but not in the middle of the day; eating beginning, middle, or end of the day?
What about night owls and early birds? Is one valued in your culture? Is one looked down upon? Is there a time of night when fewer people are out? Are there times it's acceptable to contact people (no phone calls after 9 PM)? Is there a time of day when everyone is expected to be up?
What parts of the culture influence these things? Is it an agrarian society in tune with the seasons and nature? An industrial society? A multi-planetary society? How do they adapt when interacting with others from different cultures?
Further Reading on Cultural Differences Regarding Time
What's one thing you consider odd about time?