养兵千日，用在一朝
yǎng​bīng​qiān​rì​yòng​zài​yī​zhāo

extensive preparation eventually pays off

  1. 养兵 養兵 yǎng​bīng
    to maintain an army
    to maintain, supply, and train soldiers in preparation for war
  2. 千 qiān numeral
    many
    many; numerous; a large number
  3. 日 rì measure word
    [measure word]
    [measure word] day
  4. ， yòng
    non-Chinese
  5. 用 yòng verb
    to use
    To use; to employ; to apply or make use of something to achieve a purpose.
  6. 在 zài preposition
    [location/time]
    Used as a linker to introduce the time, place, or situation of an action, meaning "at", "in", or "on".
  7. 一朝 yī​zhāo
    one day
    one day; once; some day suddenly in the future or past