Synonyms for On the dot:

• adj.

  •early (adjective)
  • too soon,
  • pronto,
  • briefly,
  • unexpectedly,
  • Oversoon,
  • betimes,
  • bright and early,
  • ANON,
  • in time,
  • shortly,
  • with time to spare,
  • in advance,
  • beforehand,
  • early bird,
  • presently,
  • previous,
  • ere long,
  • prematurely,
  • pre-existent,
  • soonest,
  • before long,
  • a bit previous,
  • far ahead,
  • in the bud,
  • in good time,
  • quick,
  • soon,
  • Proximately,
  • on short notice,
  • directly,
  • ahead of time.
  •prompt (adjective)
  • swift,
  • instant,
  • apt,
  • vigilant,
  • unhesitating,
  • precise,
  • rapid,
  • efficient,
  • eager,
  • timely,
  • watchful,
  • alert,
  • wide-awake,
  • expeditious,
  • ready,
  • smart,
  • brisk,
  • on time,
  • on the ball,
  • willing.
  •punctual (adjective)
  • periodic,
  • cyclic,
  • steady,
  • recurrent,
  • conscionable,
  • fussy,
  • painstaking,
  • dependable,
  • exact,
  • regular,
  • strict,
  • punctilious,
  • reliable,
  • on schedule,
  • conscientious,
  • meticulous,
  • accurate,
  • under the wire,
  • particular,
  • heedful,
  • careful,
  • scrupulous,
  • constant.

• adv

  •early (adverb)
  • in bud.
  •sharp (adverb)
  • smack dab.
  •without delay (adverb)
  • right off the bat.

• adv.

  •early (adverb)
  • speedy,
  • untimely,
  • anticipative,
  • seasonable,
  • preexistent,
  • direct,
  • precocious,
  • anticipatory,
  • before appointed time,
  • premature,
  • unanticipated,
  • preceding,
  • Matinal,
  • unexpected,
  • immediate,
  • overearly,
  • precipitant,
  • immature,
  • advanced.
  •exactly (adverb)
  • on the nose,
  • indeed,
  • altogether,
  • totally,
  • correctly,
  • utterly,
  • completely,
  • faithfully,
  • absolutely,
  • right,
  • positively,
  • definitely,
  • wholly,
  • precisely,
  • carefully,
  • square,
  • just,
  • truly,
  • scrupulously,
  • quite,
  • for sure,
  • severely,
  • specifically,
  • strictly,
  • literally,
  • bang,
  • expressly,
  • truthfully.
  •immediately (adverb)
  • on the double,
  • thereupon,
  • away,
  • rapidly,
  • instantaneously,
  • in a new york minute,
  • summarily,
  • forthwith,
  • in a flash,
  • PDQ,
  • now,
  • instantly,
  • straight off.
  •promptly (adverb)
  • swiftly,
  • right away,
  • flat-out,
  • straightaway,
  • Posthaste,
  • quickly,
  • fast.
  •right off the bat (adverb)
  • right off bat,
  • right the bat,
  • right bat.
  •sharp (adverb)
  • suddenly,
  • abruptly,
  • accurately,
  • smack-dab,
  • squarely.

• Other synonyms:

  •
  • punctual,
  • well-timed,
  • just in time.
  •
  • duly.
  •
  • sharp.

Antonyms for On the dot:

• adj.

  • early
    later, late.
  • prompt
    delayed, lethargic, tardy, apathetic, slow, unprepared, negligent, sluggish, unwilling.

• adv.

  • exactly
    indefinite, doubtfully, inaccurately, inexactly, questionably, incompletely, partially, dubiously.
  • immediately
    never, eventually.
  • promptly
    slowly, negligently.