Is there a word for start and end of a time period? [closed]

• Beginning and end, are the most general terminology.

• Prologue and Epilogue are literary-inspired words that have a similar meaning of bracketing the period (or story).

• If it's related to an event, you might have setup and takedown times.

• One convention for calendars is the contractions AX and BX, where BX is time before before event X and AX is time after the event. However, such events are usually short or marked at some overly-precise time.

  For example, the Gregorian Calendar has BC and AD, meaning Before Christ and Anno Domini, the Year of our Lord. Or, if you are secular or follow a different religion, BCE (Before Common Era) and CE (Common Era) are common substitutes.

  The calendar is marked in terms of the Brith of Jesus. Star Wars's Expanded Universe marks years in terms of the Battle of Yavin, as BY (Before Yavin) or AY (After Yavin).

• Sports teams will often have a warm up and cool down around working out, practicing, or playing.

• Space missions use a clock centered on the planned liftoff time, so time before that is T-x and time after that is T+x.

Do any of those fit your situation?