Opposite words for postpone:
limit, do, hurry, abbreviate, contract, shorten, act, work, deal, hasten, decide, abridge, reduce, conclude, curtail.
Usage samples:
  1. But " in the interests of the State and of the Empire we will postpone active measures."
    "John Redmond's Last Years", Stephen Gwynn.
  2. I was compelled, however, by force of circumstance, to postpone the battle for awhile, because Mr. Stelfox Steele had unexpectedly arrived in London.
    "First Person Paramount", Ambrose Pratt.
  3. Postpone the driving- party, or make my excuses; I shall not leave my rooms to- day.
    "A Terrible Secret", May Agnes Fleming.
  4. She could be engaged at once, if she liked, even before she wiped the water from her face, or she might postpone it, to let Tommy share.
    "Tommy and Grizel", J.M. Barrie.