There are no exceptions to this, not even husbands, boyfriends, relatives or friends. Make your workplace smoke free if possible. Decrease your caffeine intake. Cut it to zero as soon as you miss your period. O.K. Tea also has caffeine.
Herb teas are fine if the package says that it has no caffeine.
Mountain Dew, Coke, Pepsi and all the other colas contain caffeine. O.K. Some sodas contain caffeine so always read the label. Chocolate and cocoa may contain very small amounts of caffeine but they are O.K. to eat and drink. Decrease you alcohol consumption. Quit entirely as soon as your period is late.